i just installed a dc header in my 97 LS. i have an aem cold air intake, dc header, and a 2.5 inch exhaust. stock cat is gutted, which i had on when my car was turbo'd. i recently removed my turbo, so im going back to all motor for now. since i installed the intake and header, my exhaust is annoyingly loud at mid-higher rpms. it still has a deep tone to it at idle and low rpms, but as soon as i am in WOT is progressively gets really loud and snappy. i can wake up a neighborhood once i start hittin 5000+rpms.

would a carsound cat get rid of this problem? or would i have to install a resonator? both, maybe?

what size cat should i get? since the dc header has a 2.25 collector, i was thinking of matching up the exhaust piping with a 2.5 inch cat, but i wanted to make sure it would still line up with the 2.25 dc header collector pipe. advice needed. thanks.

 

bump

 

A resonator will help and you'll get a little help out of a cat also. The USDM DC headers are 2" not 2-1/4". The DC JDM is 65mm (2-9/16"). If you stick with the USDM header and don't mod it, then get a 2-1/4" cat.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by SMSP &raquo;</TD></TR><TR><TD CLASS="quote">If you stick with the USDM header and don't mod it, then get a 2-1/4" cat.</TD></TR></TABLE>

how would i mod the dc header? its 2"? thats even worse. haha

 

ANOTHER QUESTION...

if the dc header collector pipe is 2" or whatever... if i get a 2 1/4 or 2 1/2" cat... will it still mate with with the exhaust gasket? or does the flange allow it to connect properly?

 

cut the collector off get a new flange, O2 bung & 4-5" piece of 2.5" pipe
& make a new collector

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by S9i1R &raquo;</TD></TR><TR><TD CLASS="quote">cut the collector off get a new flange, O2 bung & 4-5" piece of 2.5" pipe
& make a new collector </TD></TR></TABLE>

hmmmm sounds like a good idea.

 

put on a stock cat and it made a difference during idle and lower end acceleration. high end is still kinda loud.