I'm constantly reading about mods people are doing to the G35 sedans and the claims in power, yet I never read anything about people putting these mods to the test on the track or dyno. I'm just curious how you guys can spend such large sums of money on headers, sedan "dual exhausts", $250 intakes, $180 UDPs, and such and have no dyno proof or track proof these things really work. I'm all for mods, believe me. Anyone that knows me on Maxima.org knows I had a good bit done to my Maxima, but everything was track and dyno tested while keeping the car sleept quiet. What I learned was catack exhausts don't do squat for the VQ motors, 3.0 or 3.5. The stock exhaust, while ugly, isn't restrictive and the variable capacity "flapper" mufflers are both quiet and unrestrictive. Intakes don't do much on these cars and the same goes for UDPs, as tested by yours truely with over 165 1/4 mile passes.

Maybe I'm missing something, but I just don't see the proof. I'm interested in gaining more power from my G35, but I don't want to make the mistakes I did with my Maxima. It took me three catback setups, an UDP, and four different intakes to realize that stock was actually best.

 

Dave, welcome to my world!!! You'll soon learn and be frustrated that most G35 drivers haven't the slightest clue about real world gains. There seem to be a lot of people who bought G35's as their first modding cars, so they seem to be stuck on the advertised gains of mods.

This is what I've concluded based on the few dyno's I've seen and my personal experiences. This all reflects mods to the 03-04 Sedan:

For power gaining mods, the only respectable mod for the Sedan (besides FI) is the exhaust. Unfortunately, the winning exhaust (The Stillen) is untolerably loud. I've seen dyno gains of around 15WHP from this all across the board (with comparable TQ numbers as well). I never dyno'd mine but the gains from the exhaust alone seemed equivalent to the gains a Maxima would receive from intake, ypipe, and exhaust combined.

I had no luck with a couple of intake mods. It raised the rice factor (i.e. loud noises) but didn't seem to make the car any faster. This includes the highly praised Stillen CAB. It made my car sound like a Civic, but it didn't seem any faster. If it was any faster, it was only minorly faster at 5000 RPM. I did notice a less smooth engine and what appeared to be less low end power. There have been no conclusive dyno's to prove any significant gains across the board on any intake. The Z-tube is a semi-worthy addition because it is OEM quality (great fit), sounds a bit better, and may gain 2-3 HP up top with really no negative side effects.

Base 6MT sedans put out somewhere in the ball park of 225-233 whp depending on the conditions. I've seen several dynos of Stillen exhaust sedans with intakes or just the z tube around 245-248 WHP. I've also seen a plethora of dyno's of people with plenum, intake, cats, headers, exhaust, ecu and they manage 247-251 WHP. That basically concludes the headers, cats, plenum, and ecu do very little. Most of this can probably be blamed on ECU programming (specifically with 6mt's). Either way it's nothing to write home about, $2,000+ for 5WHP.

I've basically concluded that the mods out there are pretty much all worth nothing except bragging rights and different sound levels. The exhaust is a decent mod, but it's just too loud. The quiter exhausts (HKS + midpipe, Fuji, Borla, etc.) make minimal gains compared to the Stillen.

DaveB, I know you, I know how you like to configure your cars, and save yourself the trouble and follow my recommendations:

Grab a nice set of performance wheels, a nicely refined suspension (like the coupe setup or a nice set of eibachs or teins), get some nice rubber, get some sway bars, and get a ztube. Call it a day there unless you want to explore FI which I know you won't. You're not a body kit kind of guy so I won't recommend the factory aero package.

The car sounds the best stock in my opinion. I have co-workers, family, and my girlfriend in my car a lot, and they all have complained with the Stillen intake and the exhaust. Stock is very mature. Making your $35k luxury ride loud isn't worth it, especially for the miniscule gains.

Disclaimer - These are my opinions only, based on my extensive research and personal experience. I've mod'd several cars and have had some worthy mods and some proven junk ones. Please consider this my opinion only and if you disagree feel free to post.

 

Yeah, I agree with what you guys are saying. Unless you want to open the engine up and put new cams, modified pistons, boring, etc., or adding a blower you're not going to see anything really worthwhile. I'm sure lighter flywheel and pulleys will add a bit, but it's not worth risking my warranty. I may upgrade to the Borla truedual exhaust, but that's it.

 

On any car with a warranty, I wouldn't even consider underdrive pulleys (let alone a crank pulley).

With standard accessory pulleys, you've immediately canned any chance of warranty on the following parts:

Alternator (and entire charging system)
Air-conditions (mainly the compressor but all parts are linked)
Battery
Electrical problems

With an crank pulley you've lost any chance at warranting anything that has to do with any engine failure.

Those chances aren't worth the few WHP gains.

 

with y-pipe, crank pulley, k&n drop in, and z-tube, i dynoed at 245 rwhp and 244 tq.....however, it was on a dynojet(apparatus attaches to rear wheel hub) for my 04 6mt sedan.....for sake of arguments, lets say minus 10 so i'm realistically at 235 rwhp and 234 tq........does this hp and tq sound about right with these bolt ons?

there's too many variables regarding dyno #s unless subject vehicles are ran at same, same day, same dyno......for me, i'm more into what the difference in hp and tq numbers are between a base 04 6mt sedan and a modded one.........with regards to cat-back exhaust system, i wouldn't spend much $$ on them after a guy dynoed with and w/out one back to back.........result? iirc, it was loud as heck and it showed a whopping 2hp gain!! this was on a vq 3.0 so take that however you want...........
intakes....i believe that the oem set-up is pretty well laid out feeding direct air from the outside, go with k&n panel filter, take that power duct piece out, get a z-tude, done..........imo, cone type filter located inside engine bay will just suck in hot air, unless sealed off so.....

crank pulley, less parasitic loss, less energy for engine to do.......had one on my 2k maxima 5sp se for 3 years, not a single problem related to electrical or anything related to crank pulley.....

these are my opinions, your milage may vary...........

 

I think 235 sounds about right for your setup. Basically what I'm trying to say is, for sedans it appears that 245-250 is sort of the max I've seen and that is almost always with the sedan stillen exhaust (which does yield great gains at blistering noise levels). After that, the ROI on mods is horrible.

You're right about dyno's, most of what I compare are before and afters of the same car at the same facility (different days, but it's as good as you can do).

 

Here's the results from a study Hot Z magazine did recently:

http://clint.gurgen.com/G35/2004.09....9_04_2004.html

As you can see, there were some nice gains to be had.

Personally, I think our cars are engineered from the factory to flow well on both the intake and exhaust sides. Sure, the sedan has a large mid-pipe, but that's more to control sound than it is a restriction, as is the baffled intake tube - small compromises that are easily remedied using stock parts.

I'd say the coupe midpipe is probably a good place to start, then add a Z tube with a panel filter. Both add a sportier sound with a little better flow.

From there, the best bet in my opinion would be to go with a proven chip.

For our cars, the guys at Technosquare seem to have the most experience.

http://www.technosquareinc.com/g35.htm

Together, these 3 mods would probably cost under $1000 and yield about 20hp while maintaining a semi-stock profile.

 

just to address the initial post, there have been many dyno tests that have resulted in gains. THe headers have proven gains, the TD exhaust as well. Intakes, i will agree that they make no gains, but UDP's really do make gains. Maybe not on the dyno, but as a direct link in the drivetrain, you definitely feel the quicker pickup.

Also, the sedan, coupe, and Z are almost all the same anyways. Just because there havent been dynos done on sedans specifically, doesnt mean that the mods dont apply to us.

 

Small gains at exorbitant prices. Not worth it.

 

Dude! You forgot tha grounding kit yo! mine got me hella gaynez...

(J/K!)

 

Yes there are gains to be made, but my original point was the car seems to peak out at 245-248 WHP, so you can basically combine mods until you get to that point and then you're ROI falls apart altogether. It's pretty much an ECU problem at this point and TS doesn't make a 6mt program so that's why I can't consider that.

Stillen exhaust + z tube makes around 245 WHP so adding anything else wouldn't be productive. The auto's seem to do a bit better because they have the TS ECU option which helps to sort out the problems with lean conditions with the plenum.

 

"It's pretty much an ECU problem at this point and TS doesn't make a 6mt program so that's why I can't consider that."

I believe they do.

Several 6MTs in the article I posted above say that they are running the TS ecu upgrade.

 

You can run a TS ECU on a 6mt but it's an ecu designed for the auto so I've heard it's not really the best solution since the auto and manual have different ecu's to start with. This is unless TS has recently released a 6mt specific ecu.

 

DaveB: Real world I'd stick with exhaust, crank pulley, z-tube, lighter wheels, better tires, and suspension enhancements. I have aftermarket sways and they have improved handling significantly. I'm considering springs of some type. I also have the pop charger but I think I will only use it during the colder months and switch back to the stock with K&N panel for the heat. If I'm felling rich I might go for the Stillen box just for fun. I don't expect any real world gains from this mod and think there are actual losses with the pop charger in hot weather as others have described.

Unlike BrianV I REALLY enjoy the sound of the Stillen exhaust. Words like "intolerable" are simply opinion. I'd say intoxicating. Dyno gains are proven. There wil be little doubt of the gain when you get on it. However, if possible, I would listen to it as it pushes your "sport sedan" heavily to the sport side. Obviously people have different tolerances for the noise of this mod.

I'd look at the APC plenum or the new cast version from Crawford also once they and some dynos come out. Other plenum replacements (Crawford, Kinetix) have shown dyno gains but some of the comments about how it affects the sound of the engine are interesting and most gains seem to be had at high RPM as well.

I'm getting the itch for a/v mods myself.

P.S. If you have an auto, the TCU and ECU grounding gear is a noticeable improvement as well.

 

It is intoxicating at WOT, it's annoying at anything else. Of course that's my opinion and I do have good ears I guess. If I was a real-estates agent or similar like job, there's no way I'd ever take clients in a stillen-exhaust equipped Sedan. Also, DaveB has a newborn baby; I think the Stillen exhaust is a bit much for a baby sitting in the backseat. I actually bought my exhaust from a guy who sold it because his baby wouldn't stop crying in the backseat of the car whenever it was on. He removed the exhaust, problem fixed. Again this is my opinion I totally respect yours. For me it was intolerable, when I was 16 it probably would not have been. I did make modifications to my Stillen to make it significantly quieter, but the desire to go back to stock silence was enough to make me remove it; it also allows me the opportunity to consider buying a 2005 because I love my car so much (still waiting on that possiblity though). The engine makes a sporty enough tone for me to enjoy it when I'm driving aggressively. However, when I'm cruising or have company in the car it's nice for it to be dead quiet (it is an Infiniti right?).