This was posted in the Z forum - but it is almost 100% applicable in every way to our (your) G35. Lots of good tips here for those interested in looks, performance or audio.
-------------

The author of this article is Jeff Wisener (an Associate Editor for Nissan Sport Magazine, an excellent resource for our cars.) Posted with the authors' full knowledge and permission.
  • Define your goal. Are you simply trying to make your car look nicer, building it for street racing, drag racing, autoX, track, or a show car. Maybe it is a combination of more than just one of these, if so, be sure which one is more important because they may conflict each other.
  • Set your budget. You could easily spend in excess of $25,000 on mods if you went with upgraded suspension, wheels and tires, and a Twin Turbo alone. Someone recently asked himself why he was spending so much money on modifying his Z when he could have purchase a Z06 Vette that will out perform a Z and the Vette would still have the factory warranty. Know what you want to achieve and how much you are willing to spend before beginning to modify your car.
  • Determine if you are willing to void your warranty from Nissan. Many suspension mods void anything related to suspension so if you spend $2000 on coilover suspension, be ready to accept that Infiniti/Nissan will not fix your tire feathering problems found on many 03 and 04 350Z after 5000 miles with anything but stock or NISMO S suspension.
  • Determine how much of a risk taker you are. A lot of people would love to have 500hp but how concerned are you about reliability. Your car has been designed stock to provide good performance with reliability. Nissan told their engineers to design the VQ motor to last 200,000 miles. As a general rule, the more hp, the less reliability although some would argue that fact.
  • How long will you keep your G35/350Z? In many cases, most modifications do not bring higher resale and in many situations depreciate the cars value. I have already seen several nice G35s/350Z’s with modifications of over $10,000 and then be sold off for parts bringing penny’s on a dollar due to people selling their G35/350Z months after modifying it.
Ask yourself how long you plan to keep a 2+2 sport coupe or 2 seater sports car. For most young couples, when the baby comes, the G35/350Z goes. If you have a sedan, this probably won't apply - until you start having that third or fourth or .... more kids!

Once you have considered items 1-5 above, now you are ready to begin modifying your car. The list I will make below is just a simple overview of each category. You should read up on each area using the search option and get a lot of good advice in many threads.
There are many experienced members on line that have specific expertise in areas such as stereo or wheels and tires. Use their knowledge and leave your ego off line. All of us can learn from someone else.
I suggest you begin modifying your G/Z in the following order:
  1. Protecting your paint job: In case you did not know, the 350Z is known for paint chipping in the front bumper. It will happen within the first 1-2000 miles and I doubt you will get it covered under warranty. I strongly suggest you think about protecting your paint. I do not personally like black bras on the front. I like the clear bra type product which provides a clear film of protection to prevent chipping, just like provided in front of your rear wheel well by Nissan from the factory but this is a thinner material. Go to http://www.clearbra.net/home2.html and check out this product. There are different brands of course and I picked one and I am happy with it. Maybe you will pick another product and find it is excellent as well? My only suggestion is get it from a certified installer of this type of product. That does not mean a window tint installer. Just because you can tint windows does not mean you can apply a clear bra.
  2. Tinting windows. Do a search on find out what percentage of tinting is legal in your state. This is another cheap modification that can be done right away
  3. Tires and wheels: This is a great place to start doing the bigger type of modifications. It will enhance the appearance and performance of your car and for the most part will not negatively affect reliability. If you are adding a body kit to your car, it would be wise to decide which one and how if any this affects your wheel and tire selection. You don’t need to know as much about wheels and tires to select them (as compared to designing a twin turbo for your car) although there are many issues to consider but even if you make a choice based on personal taste, you wont blow up your motor!
    • Wheels: If you are most interested in looks, 19” might be your best bet. Just remember the 2 negatives of 19” tires. Negative #1 is you will run a very low profile tire thus more likely to bend a wheel (and ride a little rougher). Negative #2: weight of wheel is greater and for every 6lbs you add to a wheel/tire, you lose 1 hp. If you want a combination of looks and performance, then 18 wheels might be a wise choice. You get a slightly lighter wheel thus a little more hp but it does not have as aggressive of a look as the 19” wheels. If you want the maximum performance then 17” wheels put the most hp to the ground. For those that want optimal appearance for the street and optimal track performance go with 19” street wheels and tires and separate 17” track wheels and tires. Again, what is your goal and budget?
    • Tires: The most common tire size upgrade is to a 245 ft tire and 275 rears. Notice the rears are larger than the front to maintain the understeer/oversteer issue.
    • Tips: Your stock wheels will not accommodate this big of a tire thus read up on what size wheel works for the tires you want to put on your car. I strongly suggest you use this website http://www.miata.net/garage/tirecalc.html This site will tell you how much difference there is between your stock tire and tire you desire. If you increase or decrease your tire size over 3% of stock size (in outsize rolling diameter) it will affect your ABS braking system and VDC. Simply put, your car will sense the back wheels are rotating too quickly for example and the ECU will think you are spinning your tires/losing traction which will possibly cause your car to brake or cut off the throttle. I recommend you keep the margin within 1.5%. I went with larger tires, 265 fronts and 295 rears. This is not as wise a choice for performance if you plan on maintaining the stock motor however if you plan on adding at least 100 hp, it might be something to consider. You need to be careful going with this large a tire combination. Your wheel offset must be just right or your tires will rub against the fenders. Mine don’t but I did my homework.
  4. Suspension: Now that you got your wheels and tires, you might think that gap between your fender and wheel is too big! In addition, most of these suspension upgrades tend to get rid of that annoying freeway hop found on stock 350Z’s. For many, the biggest added bonus is improved handling. If handling is important to you, add stiffer sway bars while you are adding suspension. Again just as with Wheels and tires, suspension options are on the market now so why not start here before adding hp. Here are your options:
    • Springs: Companies like Eibach and B&G have springs that will lower your car and make it look great. Costs on these springs are about $200-$250. There are strings attached. Eibachs lower your car 1.2” in the rear and .8” in the front and remember, anything over .8” drop will make your camber impossible to be within factory camber specifications. You can drive it with springs only and lose up to 20% tire life (inside edge of tire will wear out first) or get camber kits. These kits will cost you in excess of $400 for just rears or fronts. If you add these camber kits to the cost of the springs, this option is not as cheap as you might first think. Another negative of lowering beyond .8” is going over speed bumps and bottoming out. This option is good for those whose priority is looks. Make sure to get a 4 wheel alignment after installing springs.
    • Spring/shock combo: Right now, the number one option in this group is NISMO S suspension. Cost about $1300-$1800 depending on the vendor and most will ship them to you. The suspension lowers the Z about .8” thus no camber issues, no need to get alignment after install either. This gets rid of fwy bounce as well. NISMO maintains factory warranty and handles very well on street as well as track. The negative of this option compared to Coil-over springs is lack of adjustment in height, ride hardness, etc.
    • Coilovers: Cost varies from about $1600 to over $2000. You can control ht and ride. Teins even have a feature called EDFC which allows you to adjust ride hardness within the car as you are driving. You can preset it to 3 levels too such as casual driving, aggressive street, and track. JIC’s seem to be the choice of those with track being their number one priority but remember it is stiff so if you don’t want to feel the road, consider something else besides JIC’s. These are just two options, every month new coil-overs are being introduced to the market. Maybe SportZ magazine will have a shoot out on different suspension systems later like they did on exhausts and it might make the choice of selecting a suspension system an easier task then it is right now.
    • Addenda: Tanabe now has a very interesting coilover/electronic control that competes squarely with the Tein coilover/EDFC combo. This combination is based on Tanabe's Sustec Pro Seven coilovers, which come in a 'regular' street/track model and a 'hard driving' mode that adds higher spring rates for vehicles that are primarily for track purposes, and the TEAS (Tanabe Electric Active Suspension) in-cabin control box that allows the driver to change the dampener settings without having to stop the car, remove the wheels and manually adjust those settings. Tein's EDFC controller does this as well, but what the TEAS system adds is 'active mode' - in which the dampener settings are automatically changed without driver intervention *while* on the street/track when certain pres-set 'trigger' speed points are reached (up to nine can be set!) Another advantage in using the TEAS system is that it allows up to 25% more stiffness in the dampener settings (0-16 as opposed to 0-12 in the non-TEAS Suctec Pro Seven coilvers.)
  5. Stereo: The stock stereo is weak, many are not happy with the Bose as well. Many good options on stereos are available right now so you can’t go wrong. This might be your first choice to modify your car. After all, what is better than listening to good tunes in your new Z? There too many speakers, amps, and head units to list and compare in a brief overview. Again, read up on the options you have, and ask questions. Many people have upgraded their stereo already including me and would be more than willing to advise you. I had a sub woofer enclosure made that I feel is one of the best modifications I have done to date. Again, do your homework to get the desired effect.
Brakes: Before adding a lot of hp, you might want to consider being able to stop your car better. Both the stock brakes and the brembo's found on the Track model are excellent brakes. If all you are planning on doing is driving on the street and braking hard only during emergencies, than your stock brakes are as good as you need. With that being said, then why should you consider upgrading your brakes? Two reasons; the most important being if you do repeated hard braking on mountain roads or on a track, you might experience brake fade which simply means that as the brakes heat up, they take longer to stop. The more they heat up, the less they stop. The best way to determine if you need brakes upgraded is to track it. I drove my Z at the track for 30 minutes on, 30 minutes off all day long. Even after that, it took all day for them to begin to fade. In other words, who might need better brakes but unless you brake hard frequently, you most likely don’t. Another reason to upgrade brakes has nothing to do with stopping, it is for looks. Many of the people that upgrade to 15” brake kits are doing so for looks. As I stated before, 17” wheels are optimal for tracking your car. 17” wheels can only accommodate 13” rotors thus adding 14” or 15” brake kits force you to track your Z with less than optimal tires and wheels. 13” rotors on most after market brake kits will meet all your stopping needs on the street and track. If you are never going to run 17” wheels, knock yourself out and get those bigger kits if you like, they look awesome. Brembo, Stoptech, AP, and others all have kits starting at about $1700 for front brakes. You can get a 4 wheel brake set but the front brakes are the most critical. You might want to consider changing your brake lines and fluid as a cheaper alternative than an entire brake kit.
  • Addenda: Brake upgrades don't have to be in the form of a full kit upgrade - one can update individual components of the brake subsystem such as lines (going to steel-braided lines to give a firmer pedal feel and more general heat resistance), rotors (higher temp alloys, slots and other venting to increase the dispersion of heat), calipers (more pistons or just replacing worn and fatigues ones just as one might do to rotors) and on to higher temp brake fluid (DOT 4 or DOT 5.1, synthetic or ABS-friendly fluids.)
  • Addenda #2: Lastly all you may need is a more appropriate pad - either one that dusts less so you don't have to clean your wheels as much (brake dust corrodes!) or a higher-temp-capable pad for AutoX and track days. The two qualities - less dust and higher temp capacity - unfortunately do not really go together well. You either get a pad that dusts less and is really only for normal street use or you get a pad that usually dusts more but can handle the higher temps encountered when braking during performance events like AutoX and Drivers' Events. There are lots of good pads out there - Hawk, Porterfield, Axxis, Brembo, Carbotech, Pagid, Mintex and Ferodo are just a few of those available.
  • Addenda #3: Rotors are available from Stop-Tech, Disc Brakes Australia, Brake Pros (Stillen), AP Racing, Wilwood and Rotora. Brake lines are available from Goodridge and Earl's as well as other manufacturers.
We'll take on the subject of Drivetrain and Engine Modifications separately - it's here where everyone starts to drool. But it's also here where some unfortunately start to cry (and not joyful tears either!) To make sure the liquids you (and your car) release are happy ones, read carefully and get as much information as you can, especially about forced induction (FI) and transmission modifications!

Great 'how to' books on turbochargers and superchargers have been written by Corky Bell. Search on Amazon or Barnes & Noble for his books - they are marvelous guides on how to install, test and even design forced induction systems. A. Graham Bell (no relation) has written more technical and theoretical books on turbos and superchargers - get these books if you REALLY want to know the theory and engineering behind forced induction.

Drivetrain/Engine modifications: I listed this category towards the end for good reason. The first reason you should be getting use to your car in stock form and learning its limits before adding hp. I felt I need to add hp to my Z the very first day I drove it off the dealer lot. Not until I took it to a track did I realize the full capabilities of my 350Z. I found that while I was driving it, the main performance modification needed to be modified was me, being the driver learning how to drive it to its full potential. Honestly, if you care anything about performance, you should take your Z to the track. No matter how aggressive you drive on the street, driving it on a track allows you to push it much harder and in a safe environment. Besides that, it is a blast to do. There are new options in this group being released almost daily. The Vortech SC has been released; the Greddy TT is out as is APS . Other SC and ST/TT kits are out including Jim Wolf Technology, Turbonetics, Stillen and ATI.
  • Addenda: More and more kits are available every day - now JWT (Jim Wolf Technology) has single and twin turbo kits available for the G35. JWT is one of the pre-eminent manufacturers of performance parts for Nissans and Infinitis here in North America.
Waiting a little bit to add other modifications is not a bad idea. Let’s go over the options:
  1. NOS: Do you want cheap HP and your desire is to beat that Mustang next to you? NOS is an option you should consider. Some people dislike it but no one can disagree that it adds hp for short bursts and does it cheaply.
  2. NA: Some people think real engines are Naturally Aspired (NA). For those people, NOS is just flat cheating and SC and TT cars are better but have limitations. Every one of these options has pros and cons or there would only be one option. Here are the pros/cons of NA: SC and TT may have a tendency to run hotter. There is a question of reliability when you FI a motor. The 350Z VQ motor was designed as a high compression motor yet FI motors run optimally as low compression. With a NA motor, you do not have the “turbo lag” often found on TT. This turbo lag can be an enemy on the track. Most people that decide to add hp by NA often state it as being more dependable and predictable on a track. The negative is cost. Expect to spend approximately $5000 to add 50-60 hp. In addition, as soon you you add cams, your motor warranty is void, even if it is a NISMO cam because the NISMO cams are type R which is for racing thus no warranty as compared to type S which are for street and maintain the factory warranty. Other mods may or may not void your warranty. You do have rights under the Moss-Magnusson Act passed by Congress that forces Nissan or Infiniti to prove your mod caused any problems before they can void your warranty or deny warranty coverage. However Moss-Magnusson can be superceded by riders just like the application of Nismo R or other non-street modifications (test pipes are another example.) Make sure that you're aware of the impact any modification may have on your warranty. Typical NA mods include exhaust and headers, cams, pulleys, air intakes, and plenum. Try to anticipate (or at least allow for) where your goal of engine modification might lead. Some mods may not be compatible with forced induction for example, those with AT models may want to strengthen their transmission before putting in a supercharger or turbocharger, etc., It will make the modification process easier (and possibly cheaper) if you know that you are eventually going NA, SC, or TT before you begin putting in modifications!
  3. Superchargers: There are two types of FI, Superchargers (SC) and turbos which are most often twin turbos (TT) on 350Z’s. A lot of debate is covered on various threads concerning advantages and disadvantages of SC vs. TT. Some people tend to be very pro – supercharger and others are pro TT. I will try to be as objective as possible but I am sure my opinion will differ from others.
    • Supercharger kits typically run about $4800-$6000 + installation takes anywhere from 8-20 hours labor depending on the kit thus figure at least another $1000 in labor to install. All of the kits either come with an intercooler (IC) or can be added as an option to the base kit. I strongly suggest you get the IC since it keeps the motor running cooler and cooling is a major issue for any FI motor.
    • The two most common types of SC used on the G and Z are the centrifugal SC and the Roots type SC. The ATI Procharger and Vortech SC are two of the more popular centrifugal SC kits available. Both of these kits put out approximately 350-370 rear wheel hp (RWHP) at 7 psi of boost. Adding the approximate 17% loss from the crank to the wheels, that would equal about 409 to 432 rwhp. This is a significant jump over the 287 crank hp (approximately 230-245 rwhp found on a stock 350Z). Both of these kits void the engine warranty by Nissan unless you can find a dealer that will sell you them installed on the car when it is new. The significant difference between the centrifugal SC and the root is the centrifugal SC does not have full boost until you reach higher rpm’s. To be simplistic, a centrifugal SC has 1 psi of boost per 1000rpm being the peak boost is 7 psi. Boost increases hp thus a centrifugal SC really kicks in when it is above 4500 rpm since it is then approaching full boost/ peak hp.
    • The other type of SC is the root. The current root SC available is made by Stillen. The root blower is positioned on top of the motor as compared to the centrifugal SC that is located off to the side of the motor. The Stillen SC sets so high on top of the motor that to install it the hood has to be cut out and a scoop added or an entire hood has to be installed. Root type SC have full boost at low to high rpm thus more low end grunt. These SC kits tend to put out less peak hp by approximately 20-30hp but advocates of the root type blower will say that the root SC provides you with more power where you need it rather than a little more hp right before you shift. The Stillen SC will provide you with an engine warranty if you do not boost it over 5.5 psi but then you will be putting out approximately the same hp as a built NA motor. Stillen has released an IC for their SC kit which creates more hp. The warranty would be void with this set up so it comes down to hp vs risk level. that is a choice you must make based on your needs and comfort level. With all of these FI kits, tuning and boost seem to be critical issues related to reliability.
    • One cannot stress enough that an experienced tuner should be used to install these kits. Before doing that, you should read hours and hours of posts and anything else you can get your hands on before selecting a kit and an installer. Do your research and ask a lot of questions before you decide on a kit. If you raise the boost, most of these SC kits have the capability to exceed 500hp. The other side of the coin is if you raise the boost, are you keeping within the specifications of the kit your purchased? Even adding a simple addtional modification might cause problems with a FI kit. Be sure to talk in detail to the manufacture and installer before doing anything. Something you might think is ok to do might not be ok and cost you thousands of dollars to repair. As with turbos, I strong suggest that if you exceed 7psi of boost, you consider modifying your pistons, rods etc to maintain durability.
  4. Turbochargers: for the person that wishes to build the ultimate hp capable in the VQ, the TT is their most likely choice. Boost can be modified on a SC by changing the pulley but it is simpler and quicker in the TT. You simply dial it in sitting in the driver seat. The two most commonly discussed TT kits currently are the Greddy TT and Jim Wolf TT. Both of these kits cost approximately $7-8000 and then installation needs to be added to that cost. The TT has the potential to exceed 800hp. Before you dream of just turning up the boost to get those numbers, strongly consider building the internal portion of your motor to accommodate that power output. You better know what you are doing if you are putting out this much hp. An improperly tuned motor putting out this much hp is a time bomb waiting to explode. APS and Turbonetics also have highly regarded turbocharger kits out as well now. (Note: The JWT Turbo is now available for the G35. - Riff 1/06) Some kits have been out longer than others - be wary of kit that is brand new to the G or Z - even if it comes from a 'name' manufacturer, if it doesn't have a 'track record' you may be sorry you bought it. The Turbonetics kit is the only single turbo kit available for the G35.
    • Debates over how much boost should be run still rage on. To be blunt, everyone has their opinion but the fact is it all depends on proper tuning and experience dealing with the limits of the VQ engine. Motors will be blown up defining those limits. While some still argue the VQ is extremely limited in the amount of boost it can take, others feel it is a question of proper tuning and once tuners get a better handle on the ECU (car computer) and can control the fuel management, they will be able to safely increase boost to higher levels.
    • It is probably a good idea to modify your brakes, wheels, tires, and suspension first before installing FI - this is because you want a car that can handle a non-stock engine, and that often requires non-stock suspension and brakes, tires, etc.! In my opinion, if you want only 400 – 435 crank hp and you are on a budget, the SC kit might be a wise choice. If you are desiring the ability to exceed 500hp with unlimited options in tuning, the TT kit may be a better choice for you assuming you can afford it.
    • There is now a single turbo kit for the G35 and Z - Turbonetics makes it and it may be appropriate for your needs. This is particularly true if you have a tuner experienced in Turbonetics installs convenient to you. Single Turbo units have some inherent advantages - fewer parts and shorter install times. The Turbonetics kits also can use factory exhaust manifolds, further reducing costs. The historical disadvantage of a single turbo is that it must generally be larger - and slower to reach operating RPMs - than their twin turbo brethren in order to approximate the same level of power. One can seek to lessen that 'lag' with some 'tricks' but that is beyond the scope of this thread.
  5. ECU: Several companies have worked on improving the ECU. It is set from Nissan at safe levels for availability of gas (91 octane or higher) and different climates and altitudes. Nissan sets the ECU to safe limits for all of its owner’s not maximum hp output for car enthusiasts like many of us on this site. People that modify their cars for maximum hp tend to want to push those margins of safety closer to the limits of what are considered safe for most consumers. You can expect modest hp gains from an ECU being reprogrammed on a stock G or Z. An ECU preprogrammed for a FI or built NA motor will most likely result in higher hp gains than stock. TechnoSquare (TS) and Altered Atmosphere Motorsports (AAM) are the two companies that currently have offerings available.
  6. Other drive train modifications: After adding 100hp by FI to your motor, you will most likely be forced to replace the clutch to be able to accommodate that power. In addition, some like a lighter flywheel instead of stock. The bottom line is your 350Z was designed to accommodate 287 crank hp. The more hp you add, the greater strain you are adding to your entire drive train. The fact is, the weakest link breaks thus if you are putting out additional 100 hp and rev your motor to 3000rpm and drop the clutch, something might break since it was not designed to handle that power.
We hope this helps you. We have tried to be specific enough to give you a basic idea of options you have in modifying your G35 or 350Z. Of course, we did not get too specific assuming you need to do some research on your own.

Good luck and enjoy your G or Z be it stock or modded.
---------------------

Once again, thanks to Jeff for providing this great primer for modifying our cars.

This modification guidelines thread is a 'work in progress' - look for plenty of additions in the future from experienced modders amongst our FA clan!

Addenda A added 1/30/2006
Addenda B added 10/24/2006

- Riff