2.5inch Dump Pipe R34 Gtt Restrictive Compared To 3inch?

[vudoo]

hey guys

just wanted to kno as the title suggests, how much more restrictive, if noticeable at all would a 2.5 inch dump pipe be compared to a 3inch dump pipeon a r34 gtt...

assuming from front pipe all the way back is 3 inches

stock turbo

[GTScotT]

on a stock turbo it would not effect it a great deal. im assuming a mean an aftermarket 2.5" dump which would still be a long way ahead of the OEM item.

moving to bigger turbos, perhaps even a hiflow, you may find it to hold back SOME power. I do stress the word SOME, the tomei expreme dump for evos is only 2.5" ID and has been used to 300 all wheel kw and more without restriction.

[vudoo]

that's right an aftermarket 2.5 inch dump. jst having trouble finding a dump pipe that is 3inches, front pipe and cat back can get 3 inches..

[Munkyb0y]

one piece dump and front. theres a few around. here's one example. http://justjap.com/store/product.php?produ...at=0&page=1

[HEKT1K]

on the stock turbo i can't see it making a world of difference, as long as you have junked the bs stock dump (wastegate gases exit and run into a WALL) you'll probably be right with the a/m 2.5"

[vudoo]

one piece dump and front. theres a few around. here's one example. http://justjap.com/store/product.php?produ...at=0&page=1

yeh seen that but already got the front sorted...

[Harey]

Yeah me too, but I am just doing to ditch the front pipe and sell it. I will be using a bigger turbo though, so 3" dump is a must.

[perzn_34]

i use a hks gt-rs turbo on 13psi and a full 3 inch exhust but stock standard dump pide. idono why thats how i got the car but im looking into changing it to a 3 inch dump. is thier much difference between the split dump pipe and the bell shape?

[Harey]

i use a hks gt-rs turbo on 13psi and a full 3 inch exhust but stock standard dump pide. idono why thats how i got the car but im looking into changing it to a 3 inch dump. is thier much difference between the split dump pipe and the bell shape?

There is lots of info on this forum. My summary is get a belmouth one, the split ones have caused boost creep issues and problems with the separate pipe fouling on things. Im not saying they all have this issue but there doesnt seem to be any advantage to getting a split one so why bother.

[vudoo]

will 2.5inch aftermarket dump pipe even bolt onto a 3inch front pipe?

[Hanaldo]

will 2.5inch aftermarket dump pipe even bolt onto a 3inch front pipe?

Should have same size flange, just different size pipe.

I have a similar question. Will a 2.5" cat-back be that much more restrictive than a 3"?

[GTScotT]

thats a different thing all together. the back of the turbo where gas exits is actually tiny, nowhere near 3", so having a 2.5" pipe come off that and then open up to a 3" is actually not so bad. having a complete 3" would be better but not the end of the world nor perhaps even noticable on a stock turbo.

with the 2.5" catback, it will hold back some power. the main contributor to power on a car sub 200kw is its dump and frontpipe. but keep in mind you would not want a harsh step down to a smaller diameter pipe from a bigger one, that creates big flow issues.

AFAIK stock GTR exhaust systems have been used to 285rwkw