GTR Exhaust Q

[MidnightGTR]

Ive currently got 3" dump pipes from the turbos and a 3" cat back system, still with the standard front pipes.

The zorst shop said going from twin 3" into a single 3" before the cat would be no good as it would be "too much airflow" (which I thought would be good for the system) and would just somehow get blocked going into the single 3" pipe.

Also whats the story with the flex pipe, why is it only on one pipe and does it -need- to be there? dont really know much about it.

[pnblight]

flex pipe is to stop physical stress between turbos ,i would definately keep a flex in the system and yes you only need one

i when twin 3" into single 3.5" all the way to the back, where because i couldn't source the muffers i wanted, i gutted the std muffer and fitted the 3.5 in with the std twin 2.5 stringers ,i have alway intenter to install twin 3" muffer at a later stage but the system run well and is not to loud either.

you need to upgrade your front pipes as it will help spool up and top end quiet abit

pete

[DAN00H]

I've got 3inch front pipes from my turbo dumps, NO flex joint - seems to be fine on my car. I understand the flex joint makes it easier to get the pipes onto the dumps. either way, your choice - but yes get the front pipes (as large as you can go).

The rest of your system should be at least 3inch from the end of the front pipes back, bigger if possible (need to take into account the cat and mufflers). I have 3 inch cat and mufflers, quiet and works well.

[MidnightGTR]

so you have 3" dumps into 3" y piece and 3" cat back?

I cant see how what this guy is saying about you cant go 2x 3" pieces into the one, sounds stupid to me.

[DAN00H]

so you have 3" dumps into 3" y piece and 3" cat back?

I cant see how what this guy is saying about you cant go 2x 3" pieces into the one, sounds stupid to me.

No, my two 3 inch front pipes collect into a 3.5 inch, I've just got it going down to a 3 inch as that is what the Cat and Mufflers were at the time.

My system was like this as it had a straight 3.5 pipe from the collection of the two front pipes when I got it from Japan. I'm thinking of putting my old 3.5 inch back on and getting a larger cat (4in?), along with a 3.5 or 4 inch muffler.

[MidnightGTR]

ive never heard of anyone having 4" dumps, so how are you meant to have a full 3" turbos back exhaust on a gtr.

I got 3" dumps and 3" catback, seems a waste putting 2 1/2" y piece on it in the middle and making the 3" cat back useless? or would it still work ok?

[DAN00H]

ive never heard of anyone having 4" dumps, so how are you meant to have a full 3" turbos back exhaust on a gtr.

I got 3" dumps and 3" catback, seems a waste putting 2 1/2" y piece on it in the middle and making the 3" cat back useless? or would it still work ok?

my system WAS like this- twin 3inch front pipes, merged into a 3.5inch join.

3.5inch straight through exhaust from the merge of the two front pipes, NO cat or mufflers.

I had to put a cat and mufflers on for rego and at the time I could only get a 3inch cat.

I CURRENTLY have 3in F/Pipes, collect into 3.5in, 3in cat, 3in pipe 2x 3in straight through mufflers.

What I'm THINKING of doing is 3in F/pipes, collect into 3.5, 4in cat (one of those magic cats? for heaps of flow!), 3.5 pipe, 3.5 or 4in muffler (whatever is available).

the very best setup is the 3in F/pipes, collect into 3.56, then 3.5 pipe - but this is not legal.... (sounded awesome and boosted much better though!!).

What are you thinking of doing?

[ylwgtr2]

http://www.skylinesaustralia.com/forums/sh...ead.php?t=48275

[DAN00H]

ive never heard of anyone having 4" dumps, so how are you meant to have a full 3" turbos back exhaust on a gtr.

I got 3" dumps and 3" catback, seems a waste putting 2 1/2" y piece on it in the middle and making the 3" cat back useless? or would it still work ok?

Oh, yeah - don't go down in pipe size like the zorst guy is suggesting?!?!? you want the least amount of restriction possible! I'd suggest you get a set of brand name f/pipes and avoid the zorst guy! the F/pipes will bolt straighht up to your existing system of 3in dumps and 3in cat back (do you haev a good 3in cat?) it is something you can do yourself, but you need ramps at a minimum and it is sooo much easier on a hoist!

[MidnightGTR]

The system I will have if this fella does it is 3" dumps, into a 2 1/2" front pipes into 3" catback with highflow cat. even with the 2x 2.5" pipes wouldnt it be like 5" of air going into the 3" cat back so would still make use of it anyway? im no exhaust expert.

I would of thought you would of used 3" frontpipes also but this guy says 3" frontpipes into the 3" cat wouldnt work for some reason (although I know alot of these people just talk shit)

This guy said he can do the front pipes for about $100! whereas aftermarket ones are about $400-$600 or stupid prices. sure they would be better for performance but I would rather better value for money rather than paying absolute top dollar for a few extra kw.

[DAN00H]

The system I will have if this fella does it is 3" dumps, into a 2 1/2" front pipes into 3" catback with highflow cat. even with the 2x 2.5" pipes wouldnt it be like 5" of air going into the 3" cat back so would still make use of it anyway? im no exhaust expert.

I would of thought you would of used 3" frontpipes also but this guy says 3" frontpipes into the 3" cat wouldnt work for some reason (although I know alot of these people just talk shit)

This guy said he can do the front pipes for about $100! whereas aftermarket ones are about $400-$600 or stupid prices. sure they would be better for performance but I would rather better value for money rather than paying absolute top dollar for a few extra kw.

Don't let him sell you 2.5 inch front pipes!!!! pretty cheap, but a muther of a restriction!!! ask him to do them in 3 inch. You don't want the exhaust gases to slow after just exiting the turbos and dumps, it will slow response.

even $200 for 3inch front pipes is great! just make sure the rest of your system is at least 3inch : )

[MidnightGTR]

thats what im saying I thought all 3" would be the way to go but hes saying 2x 3" pipes into the 3" cat back wouldnt work.

I cant really say "do them in 3inch" when hes supposed to be the exhaust pro and telling me its no good.

[DAN00H]

thats what im saying I thought all 3" would be the way to go but hes saying 2x 3" pipes into the 3" cat back wouldnt work.

I cant really say "do them in 3inch" when hes supposed to be the exhaust pro and telling me its no good.

I'd be telling him exactly what I wanted!! It's YOUR car and YOUR money! I've never seen or heard of a GTR with 2.5in aftermarket front pipes, and thre is a reason for that - flow....

2x 3in does work!