i'm lookin all over for a new catback exhaust and i found a system that i really like. it comes in 2.25" only. i was told once that 2.5" was ideal? would it be that big a difference and what would the difference be? would 2.75 (2 3/4") be better than both?

 

Well if your basically stock 2.25 would probably be the best, but 2.5 wont be much better/worse. Any bigger should be kept for highly modded/FI cars.

 

2.5" is a good way to go if you plan to continue to upgrade so that you won't have to buy again down the line. 3" is for turbo apps and 2.25" is if you will probably be keeping it mainly bolt-ons without significant upgrades.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Redbone &raquo;</TD></TR><TR><TD CLASS="quote">2.5" is a good way to go if you plan to continue to upgrade so that you won't have to buy again down the line. </TD></TR></TABLE>

that is very good advise. i myself am running into this problem right now.
connecting the jdm 2.5 flange and piping to my 2.25 apex piping. its underlaping rather than overlaping. i hate it and don't want to spend more money on more piping.

 

ive heard that on FI engines that 2.5" piping is good to 250whp

 

2.5"+ piping on an all motor setup has the potential to support more power if you intend to do more than just bolt on's. the bigger you go the more noise there is though.

for fi setups 3''+ means less backpressure and more power and quicker spool.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by doood &raquo;</TD></TR><TR><TD CLASS="quote">the bigger you go the more noise there is though.</TD></TR></TABLE>

no not really...

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by USDMej1 &raquo;</TD></TR><TR><TD CLASS="quote">

no not really... </TD></TR></TABLE>

let me rephrase then...the bigger you go the harder it is to find a resonator that will fit under the car

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by excivicboy96 &raquo;</TD></TR><TR><TD CLASS="quote">ive heard that on FI engines that 2.5" piping is good to 250whp</TD></TR></TABLE>
I would have to agree since I have 248 whp on my stock 2000 Si exhaust putting 213 wtq on my boosted B16. If I were to go higher in power I would certainly increase the diameter of my exhaust though to help the system breath better.