hhhokay, so. i've got a 98 GSR...

JDM ITR header
2.5" omnipower test pipe
USDM ITR cat back.

i'm having problems with the 3-bolt flange (test pipe to b pipe) relationship.

2.5" on the test pipe, and 1.75" on the b pipe of the USDM ITR exhaust.

i'm using a 2.5" 3 bolt flat gasket (autozone status). the bolt holes line up and all, but it REALLY sounds like it's leaking.. especially when under engine braking and when goosing the throttle. i haven't had the chance to crawl under the car while someone revs it, but i'm pretty sure i know an exhaust leak when i hear one. however, this is the first time i've ever ran a test pipe.

i know i can't be the only person running a similar setup. should i use a 1.75" gasket instead? a friend of mine suggested using copper.

what am i doing wrong here? plz help.

 

did you install the header at the same time? could be on either side of the test pipe. im not familiar with the itr header. is it a 2 piece or 1 piece? check all the gaps everywhere and find out where its coming from first. my header has an exhaust leak and its where the 2 pieces separate.

 

what are you doing wrong?

IMO you are using a test pipe, you should probably go out and get a type r cat or a different cat back set up. If you only have a 1.75 exhaust then there really is no point in a 2.5 in test pipe

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by SleeperGSR &raquo;</TD></TR><TR><TD CLASS="quote">what are you doing wrong?

IMO you are using a test pipe, you should probably go out and get a type r cat or a different cat back set up. If you only have a 1.75 exhaust then there really is no point in a 2.5 in test pipe</TD></TR></TABLE>

i'm only using the test pipe because i got it with my header. i'm using a 2.5" test pipe because of the 2.5" collector on the header... What i feel that i need is a 2.5" 2 bolt inlet and a 1.75" 3 bolt outlet... but i don't think such an animal exists.

correct me if i'm wrong here, but aren't i required to use a 2.5" flange on the test pipe/cat inlet with that header? i know the donut gaskets are forgiving, but...

is nobody else running a JDM ITR header and a stock cat back?

Umar - the header is 1 piece. 4-1.

 

i dont think the itr catback is 1.75. i think it is more like 2.25

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by thabao &raquo;</TD></TR><TR><TD CLASS="quote">i dont think the itr catback is 1.75. i think it is more like 2.25</TD></TR></TABLE>

i never got around to measuring it but that was my guess.

it could just be that i'm not used to the raspy sound of a test pipe but i can definitely hear a noise that sounds like a slight leak coming from under the shifter/ebrake area.

 

start up the car get down to look and have a friend with a towel cover the exhaust tip momentarily. you should be able to hear where the exhaust gas is leaking from.

 

a stock ITR exhaust is not 1.75 inches...its more like 2.25

As for the cat to b pipe, you should have virtually no problems, since mine bolted up perfectly with the right 3 bolt flange.

 

if you wanna get rid of the raspy sound, put on a longer resonator. or better yet, get a high flow cat, you wont loss much flow and will dampen out the rasp.

 

after i finish writing these 2 papers i'm gonna go mess with it some more. the more i think about it, the more i think it's just the raspy noise of the test pipe that i'm not used to... but i'll find out for sure later.

JDMtypeRDC2- what size gasket did you use?

i think i'm ultimately going to have to just bite the bullet and buy a hi-flow cat and be done with it. i was hoping that having the OEM ITR b pipe with it's 2 resonators would help keep it from sounding raspy. oh well.

 

i have a similar set up and mines isnt raspy. maybe look into making a resonated test pipe should be an easy affair to weld on some flanges

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Slain &raquo;</TD></TR><TR><TD CLASS="quote">i have a similar set up and mines isnt raspy. maybe look into making a resonated test pipe should be an easy affair to weld on some flanges</TD></TR></TABLE>

what kind and size gasket did you use between the cat/testpipe and b pipe?