Hi guys,

I just got my 03 G35 Coupe and i am ready to start modifying it. I dont have a ton of money to mess around with either. I have been researching exhaust systems and the like, because I would like to make the exhaust more agressive sounding, while adding some power. However, from what i have read, it seems like the stock catback exhaust is rather unrestrictive and there are little gains to be had. So, my question is, if not in the catback, where are the bottlenecks in the stock exhaust system? What single item... test pipes, a y pipe, or headers, would net me the most gains?

My other thought is this; I really like the sound of the stock exhaust, its just not loud enough. I also know that the cats have quite a muffling effect on the exhaust. So, if I just purchased test pipes for now (lets say Helix) and keep the rest of the system stock, would it effectively amplify the stock exhaust note? I live in Michigan, so smog checking is not an issue.

I already ordered a skunk 2 plenum spacer, now I am just looking for the next best bang for the buck mod essentially.

 

I'd say the headers or the cats. Me personally, I'd change out the headers but they are a bit difficult to install.

 

100% with out a doubt CATS.

/thread.

 

Ok I did some more research. Sounds like a stock exhuast with straight through test pipes is very raspy. So, I am now looking into resonated test pipes. So far, I know of Megan, Labree, and UTR. The UTR pipes look beautiful, and have brackets welded to them which I think is a nice touch. $285 aint bad either, although its still a lot more than the helix pipes . Anyone have expirience witht he UTR resonated test pipes?

http://performancenissanparts.com/ca...oducts_id=6021

 

headers+hf cats - you'll keep the stock note but be VERY loud and pick up a llot of powe throughout the entire curve

 

From what I have read on here the stock catback exhaust flows half way descent but you will pick up 5-6 more horsepower with a aftermarket system. The headers IMO will give you the best bang for the buck. Ive read a few threads where people have installed test pipes and then dynoed. From the graph that I saw the individual only picked up about 4 horsepower with test pipes over the stock cats.

 

+1...

 

Not to step on anyones feet but changing the headers on these cars and been proven time and time again that you dont gain $hit! you spend $600+ for parts adn install and you maybe gain 3-5hp at the wheels but you gain a lot of noise.

I would do test pipes and CAI with the spacer and you will be shocked at how much it helps. If you get Y pipe im sure it will be even better. I ran stock exhuast with test pipes for 2 years I pulled 282hp 272tq on the dyno time and time again.

So dont waste your money on headers dude but thats just view.

Good luck and enjoy the G safely

 

do what im doing....plenum spacer, K&n filter/ztube combo, headers, test pipes, and a full dual exhaust...ive only done the filter/z tube, test pipes and exhaust for now and WOW. i ll get the spacer and headers installed this weekend. some headers are supposed to be good...

 

I may end up with a full on exhaust someday down the road, but for now I am just tryng to maximize my hp/dollar and gain some agressive sound. If I did ever get headers and a full dual to go with the test pipes, I would be very concerned with the noise level. I have a friend with a 325i who had a full exhaust (which sounded very good imho). Then we installed headers, which eliminated the cats, so he essential had a straight through full dual system with 2 mufflers and 2 resonators...jesus it is the loudest 6 cyl. street car I have ever heard. He revved it while i was standing behind the car and I thought my ears were gonna bleed.

So from what I understand, this would be the list of restrictions, starting with the biggest;

1. Cats
2. Headers
3. y pipe
4. Everyting after the y pipe

thanks for the input. Anyone have dyno charts with and without test pipes?

 

Drill and tap in front of each component and measure the backpressure at WOT and high rpms. Instead of guessing.

As to cats be sure to graph the pressure changes as they heat up.........will change.

 

cats

 

actually, surprisingly the Greddy Dual exhaust is VERY quiet. with test pipes it sounds awesome and perfect

 

I appreciate the scientific approach, but I dont have the time, or electronics needed to do something that extensive. If 90% of the poeple here tell me its the cats, I'm gonna believe it.

The GReddy exhaust looks appealing to me, It was one of the ones I was interested in, along with the Fujitsubo legalis R. I know the Fuji sounds great, I just havent heard the GReddy. I do like how the GReddy is true dual...and costs less than most y pipe/exhaust combos. Any idea what the GReddy exhaust weighs? What is the pipe diameter? How was the fitment?

I am still leaning toward the UTR resonated pipes, unless anyone has a reason why not.

 

oh removing cats is one of the best mods. it not only reduces weight but also gives great gains. The fitment is great ONLY problem is the relocation of the evap box, which doesnt take long at all. about 20 mins.