my exhaust has recently fallen apart and im looking into making my own.... i was going to run a 3" pipe all the way back, no resonators or cats....but after looking at it...its friggin huge... i dont know if 2.5" would be fine, or a restriction, and would 3" be no backpressure?? right now i have a 2.5" greddy downpipe, and i had some shitty 2.25" cat back exhaust...the car ran ok, but i think it was deffinitly a restriction and im pretty sure my cat was shit.... sooooo, what do you think 2.5, or 3...i have a built high compression engine with stage 2 cams, 14b turbo (16g soon) running 8psi right now...hopefully more with a new clutch...
doug

14b custom turbo kit, modified starion front mount, 9.6:1 JE pistons/Eagle rods....running 12psi
screw flanders

as said before.
2.5" pipe will suffice for people running up to 300hp. after that you will probably need the added flow of a 3". This is by no means a magic number, but it should give you an idea as to where the 3" flow capabilities come in handy.

-97 GS (First project, 299 whp)(sold)
- 97 RS 2.6 last numbers: 306hp, 352tq @16psi (Dead, parted out)
- 99 GS OZ, Hahn Kit, 56k miles (Sold)
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- 00 Nissan Maxima GLE (Daily Driver)
- 02 Audi A4 1.8T Quattro

I have full 3" on mine and i would not go back smaller. If you think 3" is huge you should see the 4" pipe!

full 3" DP - 3"cat - 3" Apexi n1


Terry

just search man... this question has been beat to death. There was a recent discussion in the performance section covered in full detail.


--------------------------------------
know me as santiago
boosted 420a and ej2o..(my 2liter v8 eaters)

i was going to search, just didnt know if this would have been coverd....my fault...thanks for the replies
doug

14b custom turbo kit, modified starion front mount, 9.6:1 JE pistons/Eagle rods....running 12psi
screw flanders

I originally had 3" from the cat back with no resonator or anything, and it was WAY to loud (sounded like ass to me and on occasion would send flames out the back of the car when shifing). Gave me a freaking migrane every time I drove the car. I put in one resonator and it calmed it down to acceptable level(still get flames now and then).

Kevin
The old:


The new:

You have a fuel problem then and thats why you are getting headaches i bet. LEAKy exhaust

I edited to the wiki!

Yea the noise was really getting to me (not to mention that I had and exhaust leak ). Flames are a byproduct of a grossly rich mixture. A wideband sensor is on it way, and I'm sending MrSlick some money for a MS tomorrow or saturday. No more crappy fuel system.

Kevin
The old:


The new:

exhaust dump! i have a 3" dp and test pipe, after that it merges right into the stock cat and resonators. sounds perfect...very deep grumble at idle, but doesnt get obnoxiously drony under acceleration. and of course once you have a dump in there it will get alot louder when you have the gate open, but if you arent in need of full power it sould like a stock exhaust on steroids.

1995 Eclipse GS - HRC Stage 2 - Retired.
2004 350z Enthusiast / 2008 Nissan Versa SL

i have a greddy muffler...the car sounded great before...it was a quite rice i guess you could call it....i dont want anything too loud, but i dont want to be limited with performance....2.5 is starting to sound alright, but where can you find a 3" resonator?? i never knew they sold them seperate?
doug

14b custom turbo kit, modified starion front mount, 9.6:1 JE pistons/Eagle rods....running 12psi
screw flanders

You can get them from summit racing or jegs. I have the bullet model from dynomax. http://www.dynomax.com/race.stm http://www.jegs.com/cgi-bin/ncommerce3/ProductDisplay?prrfnbr=4226&prmenbr=361 It was about 40$ shipped here a year ago...

Kevin
The old:


The new:

and you put this in along with what ever muffler you have? i did like the quiteness of my car, this sounds like the way to go....how did you mount it, just adapters and clamps? thanks
doug

14b custom turbo kit, modified starion front mount, 9.6:1 JE pistons/Eagle rods....running 12psi
screw flanders

Get the 3" all the way back man. I have a modified stock DP, mated to a 3" test pipe, to a 3" Greddy Evo all the back. My car hardly makes a sound unless you tromp on it, and that's how it should be. The flow compared to my previous setup is amazing ... my boost response is so much greater than before it's not even funny.

1999 Eclipse GST 4G63

check out my video clip of my car on http://www.gsturbo.com/james/pictures%20-%20new%202005.01.30/Video/

the exhaust is the hrc 3" downpipe coupled to a straight 3" pipe, no cat, no res.. directly to a megan racing 3" inlet muffler with a 5" tip. sounds very deep. it is loud.. but hey.. when you want to push the air, you have every ability to do so. thank god i have no emission tests here.

to answer the question though.. a 3" exhaust is not over kill by any means. the best exhaust for our car is no exhaust

i was going to try and reuse my greddy evo muffler, but its only 2.25 inlet or so....i dont know how much of a restriction it would be... i think im going to just try 3" and add a resonator if its too loud...i do have emissions here, but they've never looked under my car to see if i have a cat, and i keep my car under 5000 miles so i just get an exempt sticker....
doug

14b custom turbo kit, modified starion front mount, 9.6:1 JE pistons/Eagle rods....running 12psi
screw flanders

I have the same muff as siueclipse, sounds great. My old loud one was a tenzo venturie *sp*. Was loud as shit. As for the mounting, no clamp gheto crap here, welded in right after the second o2 sensor. Cost me all of 120-140 for the whole job which included the 3" piping, labor and the two muffs. Those megan parts may be cheap but they do work.

Kevin
The old:


The new:

any good place to recomend to get a megan muffler?
doug

14b custom turbo kit, modified starion front mount, 9.6:1 JE pistons/Eagle rods....running 12psi
screw flanders

I think I paid 35$ for mine off a freak no reserve ebay acution.

Kevin
The old:


The new:

lol

_ _ _ _ _ _ _ _ _

96 Black ESi
91 Red TSI AWD (RIP)
02 WRX


"turnin wrenches for nine hours in the pouring rain, just to get the beast up and running again"

Aerospace Certified TIG welder for Precision Castparts in Portland, OR.

JoshSpair.com

great pic, turby

_____________________________________
Scott
90' GSX, 06' Effo SSL

(parting out 95 GS)

Unless you plan on taking off your turbo to go naturally aspirated, you should definately go with a full 3". Your turbo is providing enough backpressure as it is for the engine to function properly. You'd just be restricting the turbine to spin if you went to 2.5". I'd possibly even look into 4" DP. Overkill, but it doesn't restrict you turbo from boosting.