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Intakes are probably the most common and least expensive bolt on midification you can do to your G20. They help the G20 get more air into the cylinders and help mid range to top end power.

Ghetto airbox modification/Stock Airbox Mod
This modification is done to the stock airbox. This modification entails cutting holes in the stock airbox to allow more air through the factory filter location. This modification usually does not gain any hp, but rather gives the motor a nice throaty growl, somewhat similar to a WAI setup. For many this is the first modification performed.

Warm air intake - (WAI): The most popular setup for G20’s is the Jim Wolf Technology Pop Charger. This solution provides a velocity stack that bolts to the MAF housing that provides a smooth entry for incoming air. The filter element bolts to the outside of the velocity stack and sits in the engine bay behind the battery. This setup is CARB certified. There are also many low cost WAI setups available right now that are comprised of a MAF adapter and generic cone filter. You can expect about 1-3hp with any of these setups. The main difference here is noise; these will make the engine noticeably louder under acceleration.

Cold Air intake - (CAI): The Cold Air Intake is a much more potent intake. The installation is a little bit harder, but the overall results are much more pleasing. The cold air intake will make a lot more midrange power than a WAI, and more top end power as well, about double what the wai produces. The three popular CAI setups right now are made by Hotshot (HS), Place Racing (PRI), and AEM. There is also a Stillen setup, but it’s a slightly different design. The HS, PRI and AEM units replace the piping from the throttle body all the way to the wheel well. They are all make of smooth, mandrel bent piping and with the use of silicone couplers place the MAF in the center of the piping, very close to the stock location. By moving the filter to the wheel well the air entering the motor is much colder, denser air, which helps with power. As well the length and size of tubing helps with resonance tuning. Resonance tuning is very much like sound tuning, where the pulse waves coincide with the open intake valves helping force air into the cylinder.

Larger Throttle Body
This modification doesn't gain any power on the dyno, but it does help with throttle response, it'll make the car feel more responsive. The stock throttle body is already rather large at 60mm.

Larger MAF
This modifcation will not free up any power on a N/A SR20. The only reason to upgrade the MAF is if you can max out the stock unit at 5.15V. Anything short of a large nitrous kit or turbo system most likely will not be able to max out the stock MAF.


Headers are the best bolt on upgrade you can do outside of the motor. They can produce quite a bit of power, are rather inexpensive, and can be installed relatively easily.

Hotshot: Hotshot Performance makes by far the best performance header for the G20. They are dyno proven to produce the most horsepower and have gone through many revisions to “stay on top” so to speak. The hotshot unit is a 4-2-1 setup. The hotshot really boosts power output right around torque peak and gives very good top end power. Expect about 10-15 hp, depending on your setup.

AEBS: AEBS headers are older headers, but still very good. These provided very close competition to the HS header and in many argue they are a better header. They are a 4-1 design, which can cause some clearance issues on lowered cars. They do not provide any emissions revisions as well. This header helps over a very broad range of rpms and makes very close to what the hotshot makes as far as top end power gains. There are rumors that a revised AEBS header will be released and will produce more power and also provide emissions equipment bungs as well. Expect about 10-12 hp, depending on your setup.

Stillen: Stillen headers have been around for a few revisions, just like the HS units. They are either a 4-2-1 design or a 4-1 design, depending on the revision with the 4-1 being the newer one. These headers make good power as well, not quite as much as the HS units, but very close. The difference in power between the 4-2-1 and the 4-1 units is very minimal. The Stillen unit gives good low end power and will peak slightly lower in the powerband than the HS header. Expect about 8-10 hp, depending on your setup.

Pacesetter: The pacesetter header is a low priced header. It is very closely related to a first gen hotshot header. One of the models is coated with a cheap black paint that’ll burn off the first time it’s used, newer models can now be purchased with an optional ceramic coating. Expect 5-7 hp.

Other noteable headers are the S&S header (6-8hp, 4-1 design) and …. HP racing?

Catalytic converters:

Stock: This unit is very good, does not hurt horsepower at all, and helps reduce the poisonous exhaust gases; the stock cat is 2.5”

Aftermarket: The only reason to get an aftermarket cat is if your stock cat becomes clogged or damaged. They are an affordable replacement for stock. You can get a wide variety of different sized and applications. The most popular brands are random technology and Catco.

Exhaust System:

The purpose of an upgraded exhaust system is to reduce backpressure while keeping exhaust gas velocity as high as possible to increase the efficiency of the motor’s breathing capability. SR20DE powered vehicles seem to benefit the most from 2.25”- 2.5” exhaust in naturally aspirated form. Turbocharged engines like as large and free flowing exhaust as possible. The most popular and easiest size to fit is a 2.5-3” exhaust.
For any high performance exhaust you’re going to want to only get a mandrel bent exhaust system, crush bends rob horsepower and can also contribute to a raspy sound.
As for the resonator and muffler you’re going to want to find a perforated core muffler rather than a louvered muffler.
Some readily available systems that’ll bolt on to your G20 can be found through Greddy, Blitz, and VRS. There are also rear exhaust sections available; these replace your piping from the axle back and the rear most muffler as well. These setups can be sourced through companies like Remus, Sebring, Super Sprint, and Stillen. However, most people opt to have custom systems fabbed up at local exhaust or high performance shops. The most common setup right now incorporates a Magnaflow round muffler for the resonator and an oval Magnaflow muffler for the rear muffler. With a full cat back exhaust system you can expect to gain anywhere from 3-10hp depending on your other mods and stock exhaust system. This modification helps mainly top end horsepower.

Underdrive Pulleys:

Right now Unorthodox Racing makes pulleys for the SR20DE motors. They have a 2 pulley set that replaces the crank and water pump pulley and a 4 pulley set that replaces the crank, water pump, power steering, and alternator pulleys. They work by slightly under driving the accessories and also reducing rotating mass, each helping free up hp the motor normally uses to spin the accessories. A great feature about the pulleys is that they also prevent the water pump from cavitating at high rpms, stock it’ll start above 6500rpms. A must have for anyone planning to hot lap or track race their G20.
The two pulley set is good for about 4-6whp gains, climbing from a small 1-2 horsepower gain off idle, to a much larger 4-6hp at redline. The 4 pulley set is good for about 1-3hp more than the 2 pulley set, the installation is also quite a bit more difficult and time consuming. This mod is very deceiving and doesn’t feel like it helps as much as it does, due to the smooth, linear power gain, but is a great bang for the buck mod.

Lightened Flywheel:

There are two main options for this modification, lighten the stock unit to about 14lbs, or purchase an aftermarket unit that weigh in at 9-12lbs. To compare the stock flywheel is about 18-19lbs. Either setup will noticeably help your G20’s acceleration. This modification helps by reducing rotating mass, helping the motor and drivetrain accelerate faster. The purpose of the flywheel is to store potential energy and help the car start moving from a stop. However, once in motion the flywheel acts as dead weight and actually hurts acceleration. Reducing this “dead weight” helps the motor spin easier and more freely. Also, the lighter the flywheel the faster the engine decelerates as well. With a lighter flywheel you will have to rev the engine higher to keep from bogging from a stop.

Contrary to popular belief this modification will help when drag racing. You will have to adapt to rev the car higher off the line, but once in motion the improved acceleration of the car will help lower your ET’s. This mod is also great on a road course as it will help you more quickly and easily match rpms between gear shifts.


For optimal performance on a stock motor dial in between 17-19 degrees timing and run 91-92 octane gas. Once modified w/ aftermarket cams you will want to back this back down, and it will vary between cams. Jim Wolf’s regular S3 cams like lower timing, 13 degrees has given the broadest powerband in dyno tests. If you are running a Jim Wolf ECU you’ll want to set your timing to 15 degrees, unless otherwise stated on the JWT ECU.


The premiere tuner for Nissan ECU’s is Jim Wolf Technology. JWT can reprogram your stock G20 ECU for a variety of different applications. They can account for a change in injectors, MAF, the addition of cams, nitrous, a turbo kit, and even a different motor! They also can raise the rev limiter, remove the speed limiter (if there is one) and account for most changes in emission equipment.


91-92 Intake cam
This is a great bang for the buck modification for 94-99 G20's. Usually costing less than $100 for the cam, this is close to the cheapest 6whp gain you'll find. At redline (7500rpms) the gains will be approx. 10-12whp. This intake cams has 16 degrees more duration than the later model cams.

JWT Cams

-Street Grinds
These cams provide great power gains from idle all the way to redline. Depending on the grind, your power band may vary. S3's are the most tame cams, they will increase power from idle all the way to redline. They have a very slight lope at idle, and should gain about 12whp at peak, with gains as high as 25whp at redline (7500rpms). The S4 cams can be used on the stock valvetrain, just like the S3's. The S4's will gain a little more power up top and will not fall off as quickly. But, they also lose some power down low in the rpm range. The idle on these cams is a bit more rough as well.

-Competition Grinds
These are JWT's potent race developed cams. The competition series cams are the most aggressive cams available for a hydraulic valvetrain SR20 motor. They must be used in conjunction with the JWT valve springs and retainers. A JWT ECU is pretty much necessary with this modification as well, as the idle is rather rough. There is a noticeable lope in the lower RPMs and there is a loss in low end power. However, in the upper RPMs these cams will gain more power than any other cam available. These really are not designed for a street car and should be used on a built motor.

HKS, Jun, Tomei, Toda, etc..
Not a lot is known about these cams. They are usually very expensive and are difficult to find. You can find anything from mild street cams to aggressive race cams from these manufacturers. A few SE-R owners have had good results with the larger Jun cams, although they seem to be very high rpm oriented cams, just like the JWT C series cams. The Tomei cams seem to produce good power throughout the powerband, but don't appear to make quite as much power up top as the JWT S3's do. Hopefully more information will surface about these cams.

Built N/A Motors

Pistons and Higher Compression
These usually are not very common modifications unless you're looking to extract every last hp out of your motor. Going with larger pistons will slightly increase the size of the combustion chamber. For example an 87mm 300zx piston will increase your motor from 1998cc's to ~2045cc. Not much of a change, but at this point every little bit helps. Higher compression is possible with new pistons. JWT forged 300zx pistons will raise the compression to 11.0:1, up from 9.5:1 stock. This will net about a 10whp gain all across the powerband, from idle to redline. With this modification you will need a reprogramed JWT ECU in order to avoid detonation.

This is left to the professionals. Headwork will gain you power in the higher rpms. Good headwork usually won't lose any low end power. You'll most likely see anywhere from a 10-25% increase in flow. As far as power gains, it really depends on your other modifications and how extreme you go with the headwork. Some opt to even raise the compression by reshaping the combustion chambers, that will gain some extra hp as well.

Stroker Kits
These are only for the most serious of engines. They cost a TON of money and are extremely hard to obtain.

Extrude Honing
This really doesn't help too much on an N/A SR20 motor. You'll see a few hp from the power peak to redline. On a fully built motor you might see gains start a bit lower, and help more at higher rpms, but this should be seen as a final modification, where you're looking for every last hp.

Orgionally posted by JustinP10
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