dand39

What size diameter cat. converter or resonator did/do you use?

I ask because I'm getting an RSR exhaust for my 4th gen, and my current resonator's outlet diameter is 2.5". So I'm wondering if it'll be better, in terms of flow and reduction of "bottlenecking", to get a cat converter or resonator with a 2.25" outlet.

Also, how does that work out: bolting up two different size pipings together, so that piping diameter abruptly changes? I'm not too familiar with exhaust systems, so... sorry.

RSR exmag exhaust piping is 60 mm, roughly 2.36" in piping diameter, in case you're wondering.

Thanks in advance.

dand39

bump for an answer, thanks.

petern101

i'm using 2.5 with my rsr exhaust

but my greddy headers aren't 2.5 opening so it kinda doesn't matter

ckyskater733

bump for more answers..i wanna know this too.

HxClude

Do you plan on getting a header? If so, wait until you know for sure what you're getting and then buy a cat based on the header collector diameter. Basically, the Japanese catbacks don't match up well with anything - they're 2.36" tubing for the most part and nearly all of them taper down to ~2.00" or less to mate with the stock cat (including your RSR). If you have to keep the RSR, cut the last foot or so off the b-pipe (where it starts to taper down to 1.9-2.0"), get a 2.25" cat, and call it a day.

If you're really concerned about bottlenecks, sell the RSR, buy a nice header, and have a system built to match that collector diameter. Sucks, but there's not much you can do. T1R has a header, test pipe, and exhaust that all match perfectly - that would be another option. there's also the Thermal catback which doesn't taper - 2.25 all the way thru. It would mate perfectly to a 2.25 cat and header with 2.25 collector.

I guess going big to small (from header to muffler) is the best way if you can't match all your diameters. At least thats the way it always is with turbo cars.

ckyskater733

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by HxClude &raquo;</TD></TR><TR><TD CLASS="quote">Do you plan on getting a header? If so, wait until you know for sure what you're getting and then buy a cat based on the header collector diameter. Basically, the Japanese catbacks don't match up well with anything - they're 2.36" tubing for the most part and nearly all of them taper down to ~2.00" or less to mate with the stock cat (including your RSR). If you have to keep the RSR, cut the last foot or so off the b-pipe (where it starts to taper down to 1.9-2.0"), get a 2.25" cat, and call it a day.

If you're really concerned about bottlenecks, sell the RSR, buy a nice header, and have a system built to match that collector diameter. Sucks, but there's not much you can do. T1R has a header, test pipe, and exhaust that all match perfectly - that would be another option. there's also the Thermal catback which doesn't taper - 2.25 all the way thru. It would mate perfectly to a 2.25 cat and header with 2.25 collector.

I guess going big to small (from header to muffler) is the best way if you can't match all your diameters. At least thats the way it always is with turbo cars. </TD></TR></TABLE>
for me, i bought a header that doesnt match up to the stock cat. how big is the stock cat, because i want to get a resonator/test pipe that matches up to it.

HxClude

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ckyskater733 &raquo;</TD></TR><TR><TD CLASS="quote">
for me, i bought a header that doesnt match up to the stock cat. how big is the stock cat, because i want to get a resonator/test pipe that matches up to it.</TD></TR></TABLE>

stock cat is something like 1.8". You'll want to get a 2.25 cat or test pipe most likely unless you have a header with a 2.5" collector. DC Sports, Greddy, and all the budget headers have a ~2" collector. Mugen, Fujitsubo, Vibrant are about 2.25. SMSP, Hytech, RMF, etc are 2.5" or larger.

ckyskater733

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by HxClude &raquo;</TD></TR><TR><TD CLASS="quote">

stock cat is something like 1.8". You'll want to get a 2.25 cat or test pipe most likely unless you have a header with a 2.5" collector. DC Sports, Greddy, and all the budget headers have a ~2" collector. Mugen, Fujitsubo, Vibrant are about 2.25. SMSP, Hytech, RMF, etc are 2.5" or larger.</TD></TR></TABLE>
alright, so i should get a 2.25" cat/test pipe? even if my header collector is 2"? sorry i don't know the size of it, all i know is it is bigger than stock. i think its just a stock "jdm" header. i just want it to match up without bringing it to a muffler shop.

HxClude

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ckyskater733 &raquo;</TD></TR><TR><TD CLASS="quote">
alright, so i should get a 2.25" cat/test pipe? even if my header collector is 2"? sorry i don't know the size of it, all i know is it is bigger than stock. i think its just a stock "jdm" header. i just want it to match up without bringing it to a muffler shop.</TD></TR></TABLE>


I think that the JDM headers have a 60mm OD collector which will be pretty damn close to 2.25. If you're running a typical 60mm catback (Apexi, Greddy, Tanabe, RSR, etc.) 2.25 will be just fine.

ckyskater733

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by HxClude &raquo;</TD></TR><TR><TD CLASS="quote">


I think that the JDM headers have a 60mm OD collector which will be pretty damn close to 2.25. If you're running a typical 60mm catback (Apexi, Greddy, Tanabe, RSR, etc.) 2.25 will be just fine.</TD></TR></TABLE>
aight thanks man. yeah thats what i plan on doing, apexi ws2 cat back and get a 2.25" test pipe. thanks for your help