Hey everyone, i'm extremely new to this site as i've just bought a 2004 g35 coupe 6spd. I wanna upgrade the exhaust system which i believe comes with Y pipe if i'm correct. Maybe some Test/race pipes, and some headers. just a few questions.

Does the brand matter for the Headers, as i see a lot for sale and most are generic, so i dont know which ones would give me the most gains.

Same question for exhaust, which one is the best, and would sound the deepest.

I want to install some test pipes to replace the cats, but i was wondering if that would actually benefit me in power, or lose power, sometimes messing with backpressure isn't the greatest. I also want to know if i'll lose gas mileage by adding on some test pipes or exhaust.

Any help would be great!!! thanks in advance.

 

ive personally heard that crawford headers were the best out there. u might want to look into hi-flo cats, rather than taking them completely out. greddy evo and HKS are my two favorite. personally i like greddy more, but its all up to ur final opinion. there are both true-dual, as well as single->dual exhaust systems out there. i dont believe most exhaust systems come with the y-pipe as well, but double check that one as im not quite sure.

be forwarned tho, with so many "breather mods" u will lose some low-end torque, as these are mostly beneficial for the high-end.

 

as far as headers are concerned IMO crawford headers are the way to go. As far as exhaust its up to you. i have the fuji and i love it. i recommend you find people in ur area and hearing the diff exhaust and find which one you like.

 

I have heard good things about crawford headers but I have NOT seen anyone here give dyno results and I have heard that labor ranges from 400-600 dollars.

I, in the other hand wanted to see dyno results before I purchase something that expensive, therefore, I went with the Alphawerks Headers. They retail around 575 and up and if u do a search on this forum there are dyno results of +18hp gain with these headers.

I don't know if the crawford headers make more but +18hp for 600 is the best bang for your buck. As for the y pipe, there all many companies out and price ranging from 130-300. I wouldn't think there would be any performance difference when they all make the the piping 2.5-3". Therefore, I would think a mugen y pipe would be just as good as the tanabe ($300) but that is just me. Yes the more expensive one will look better but the thing is under the car so who cares.

Now for the cat, ppl have mix feelings about these HF cat but I would prefer the kinetix cats over the crawford one just bc crawford has more fitting and o2 issues. GL with your mods.

 

Thanks for all the help guys, one more big question... do these mods drain my gas???

 

If you don't change your driving habits, no. But when you mod, you'll want to take advantage of those mods and that means WOT. This in turn causes your fuel economy to go down.

 

Dyno results are here:

https://g35driver.com/forums/engine-drivetrain-forced-induction/60670-crawford-headers-cats-stillen-vb-ecu-l-spec-tons-pics-56k-warning.html

Lou

 

248hp with all that mods makes me want to just go FI. Does the 03 have 280hp or 260?

Here's a dyno of a stock AT and then one with only the alphawerks headers.

 

how does the car sound with the headers and HF cats?

 

Baseline hp on that graph seems a bit low doesn't it? Is that an 03 sedan? Cuz the 03 sedans were rated at 260hp.

 

the dynos seem low bc there was no fans on. The driver wanted to see real hp for the car and the headers. So I would assume the hp would be increased by 5 more hp or more if the fans were running during the dyno runs.