Alright, I did a search a didn't find anything that pertains to my question. So here's the story...

I recently did a R swap in an EJ coupe. The header ends at 2.5". So it won't bolt to my stock cat since it's much bigger. So, I wanted to stay stock and I purchased a JDM ITR cat. Which bolts directly on to the header and fits perfectly.

So now I have an appt. at a muffler shop to redo my piping the saturday. I purchased an ES oval muff back in early April and it's the 2.25" muff.

I was just wondering since everything I did so far has been 2.5" should I go with 2.5" piping also.

Should I go with 2.25" piping or 2.5" piping? What's the pros and cons of each particular size? I can always get a new muffler if needed be.

Any help would be great. Thanks

 

i always learned it was best to keep it all the same size,

but i cant imagine a quarter of an inch difference would change much hp wise, unless you have like 300 hp, but im not sure, so bump for this question............

 

Thanks for some info. Anyone else want's to try?

 

it will bottleneck the exhaust flow but i dont think it will hurt that much, but if you want, sell that bitch and buy a 2.5

 

oh my god. now ur thinking of selling that es oval when u just got it? u shoulda let me use it! man...ur wasting time...cause if u were to order a new muffler..it would take a week..and ur appointment is THIS saturday. i doubt it would make that much of a difference dude. hurry up already so we can go to the track.

 

No one eh? One more try before I go to the shop on sat.

 

your gonna be pushing a lot of exhaust, that bottle kneck might be fine, but then again it might be enough backpresure to float a valve or create misfiring.. just sell the 2.25 and get a 2.5

 

i highly doubt you will float a valve just cause u got a small exhaust. i was running on three runners on my header cause one was flattened like a pancake...my motor still pulls strong...and compression test came out flawless. just do it kiet....dont wait too long

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by DewMota &raquo;</TD></TR><TR><TD CLASS="quote"> but then again it might be enough backpresure to float a valve or create misfiring.. just sell the 2.25 and get a 2.5</TD></TR></TABLE>
Over reving makes valves float. It would take a hell of a lot of backpressure to make a valve float, more then would ever be possible with just exhaust.
You should be fine with the 2.25 inch pipes.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Djaric &raquo;</TD></TR><TR><TD CLASS="quote">
Over reving makes valves float. It would take a hell of a lot of backpressure to make a valve float, more then would ever be possible with just exhaust.
You should be fine with the 2.25 inch pipes. </TD></TR></TABLE>

u hear that kiet? now go do it already. by the way...can u ask the dude at red run why my cat goes clank clank...when the motor is off? it'll continue to clank every 5 minutes up to an hour until the exhaust pipe is cool. but it didn't do that the whole weekend after we went to red run. any ideas? ask if he remember if my cat was clogged or something. i dont remember.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by krazn &raquo;</TD></TR><TR><TD CLASS="quote"> by the way...can u ask the dude at red run why my cat goes clank clank...when the motor is off? it'll continue to clank every 5 minutes up to an hour until the exhaust pipe is cool. but it didn't do that the whole weekend after we went to red run. any ideas? ask if he remember if my cat was clogged or something. i dont remember. </TD></TR></TABLE>
That noise is pretty common with cats and exhausts. My parents Camery does it all the time. I'm not exactly sure why it does it but Im pretty sure it has something to do with thermal expansion and stuff cooling off at different rates.
Mine does it sometimes, nothing to really worry about.