Project G35 has never felt up to the claimed 280BHP that Infiniti advertises. On track comparisons with cars like the E46 M3 revealed a huge gap in straight line speed and it is clear that a power increase is necessary to improve on track performance and will certainly make for a more enjoyable drive on the roads. We put together a dyno test of the basic bolt-ons to see what gains are available with each modification to help you choose which ones are right for you.
Our list included the following:
Uprev ECU flash and retune (91 octane safe)
Jim Wolf Technology pop charger intake with Z tube
T1R Catback exhaust
Motordyne Y Pipe with high flow cat
SG Motorsport long tube prototype headers
Uprev ECU flash and retune
I opted to install the Uprev flash as the first upgrade on project G before the other components had arrived for the test. Our plan was to return to the original map for baseline testing however the original file for this particular vehicle turned out to be unavailable so our baseline was established with the Uprev reflash in place. Other stock 2003 G35 coupes on the same U2nDyno hub dyno have tested between 210 and 215whp so the 226.2whp baseline set with the Uprev flash produced impressive gains.
Uprev ECU = +12whp gain
The Uprev ECU is an impressive tuning solution for G35 applications. It allows your tuner to control most all engine parameters including the variable cam timing which most other tuning solutions do not support. It also allows the secondary 02 sensors to be disabled which is a huge benefit when using the SG-Motorsport longtube headers and the rearward located Motordyne high flow cat. SG’s expert tuner Sasha Anis added some timing while keeping it safe for 91 octane fuel and removed the factory E throttle cut as the G approaches redline. To help prevent drivers from unexpectedly hitting the rev limiter Infiniti closes the throttle plate at upper RPM’s. This causes performance to fall off and limits the usable power band. We also had SG increase the rev limiter to 7000 rpm and change the rev limiter settings from 200RPM drop to 50RPM drop between cuts. This makes the limiter feel less intrusive should you hit it and the extra RPM is definitely welcomed. In short the Uprev ECU offers the benefits of a stand-alone ECU tuning solution without the high cost and timely installation, not to mention drivability remains factory smooth. One important note with the Uprev is our particular vehicle seemed to be cursed and resulted in a very rare upload crash on the final tune which could not be corrected. The ECU had to be sent to Uprev where they were able to reset the ECU and once returned we were able to continue.
Jim Wolf Technology Pop Charger Intake kit
The JWT intake with Z tube is a simple installation at an affordable price that resulted in a sporty intake sound and worthy performance gains. The intake maintains the use of the Infiniti power duct as well as the center duct and features an anodized aluminum heat shield to isolate the tapered cone filter from underhood heat.
JWT in place, notice the use of the factory duct.
The intake is supported with the included bent steel bracket which does the job however a more elegant solution could be had. The Z Tube is an oem part and fits as such, very well. The smoother design helps improve flow over the original tube and together with the pop charger this is a great modification.
Jim Wolf Technologies Pop charger and Z tube +3.1whp
T1R cat-back exhaust
The T1R catback exhaust features full 304 stainless steel construction and uses a single 3” pipe feeding a transverse mounted muffler in the OE location with dual outlets. Installation was relatively straight forward however the right rear evap canister shield had to be removed to clear the outlet from the right side of the muffler. Once this was performed the tips lined up correctly with the bumper cover and the exhaust looks great.
We performed DB testing of interior noise with the OE exhaust versus the T1R and found sound levels to be equal while the tone of the T1R is slightly deeper. The relatively quiet exhaust note is welcomed and makes for easy conversation with passengers and enjoyable long drives. On the dyno we found power levels to be close to original with a 1.5whp peak gain. This was disappointing to see however we were happy to be rid of the rusty original exhaust and it should help support flow increases as the Ypipe and headers are opened up. We actually had to source a fresh OEM muffler for the test as our original had the flange break off at the muffler inlet due to rust.
T1R catback exhaust +1.5whp
Motordyne Y Pipe
Motordyne Y Pipe installed with test pipe. The Motordyne XYZ pipe is manufactured from 304 stainless steel and features flex joints to help minimize fatigue and extend the life of the pipe. The flexes also ensure the flanges are all able to mate and seal correctly regardless of tolerances between vehicles. It is available in several configurations including straight through, with resonator or with high flow cat. Because the SG longtube headers replace the original cats we opted for the version including the high flow cat to maintain emissions compliance and help do our part for the environment. We sourced a Motordyne straight through test pipe to evaluate the Ypipe with the oem manifolds and cats prior to the header install to offer an accurate idea of the performance gains to be had for someone looking to keep their oem manifolds/cats. Installation is very straight forward and while the cost is somewhat high the pipe fits well and appears to be of good quality. Sound remained very similar and decent gains were achieved.
Motordyne Y Pipe +7.2whp
SG Motorsport Longtube Prototype Headers
The SG-Motorsport Longtube headers are beautifully crafted and built for maximum performance.
The SG Motorsport longtube headers feature a race proven design and 304 full stainless steel construction. Removal of the OEM manifolds is tough as some of the fasteners are difficult to reach and can be somewhat tight after years of use.
The headers feature beautiful CNC machined flanges and each tube is mounted individually. This allows the headers to be fitted without requiring the steering rack to be disconnected and the potential need for an alignment after. We opted to heat wrap our headers with DEI exhaust wrap to protect nearby components including fuel lines and the engine starter. To achieve equal lengths with the longtube headers they need all the space available in the cramped engine bay however once in they fit nicely and the primary 02 sensors can be installed.
We were anxious to see the results as the SG headers on the same U2NDyno have produced over 30whp on the Revup version of the VQ35 however on our non revup engine we only saw 11.4whp. Some research revealed that the Revups feature a more aggressive cam profile which seems to be able to better use the increased flow that the headers provide. If installing the headers on a non-revup something like a Nismo performance camshaft set would go a long way to realize their true potential. On the road we found the longtubes add a raspyness to the exhaust note at around 3500RPM but when approaching redline sound truly fantastic.
SG Motorsport Longtube Prototype headers +11.4whp
Fortunately the G35 has received a healthy welcoming from the performance aftermarket and as shown it is possible to achieve a decent gain in performance with the basic bolt-ons resulting in a total increase of 23.2whp. Rev-up owners can count on much more sizable gains once at the header stage and non rev-up owners should definitely consider the camshaft upgrade. Our project G35 has maintained excellent street manners while achieving a noticeable increase in power output.
Related Article: Infiniti G35 Coupe Quaife ATB LSD and Nismo Diff Cover Installation