I recently installed a DC Sports 4-1 Header, Random Tech Hi-flow Cat, and DC Sports SCS Catback for 94-99 GSR in my '95 LS w/ jdm B18C. Now my exhaust is extremely loud (was using stock LS exhaust before). Starting at about 2.5K, it sounds like I'm running an open header. I thought I had an exhaust leak between header and hi-flow cat or btwn hi-flow cat and catback, but none of the bolts were loose. I used the Random Tech Install Kit (which came with gaskets for header and catback connections) and all gaskets that came with the DC Sports Catback.

Just a couple of questions.
Why is the exhaust so loud? Combination of hi-flow cat and straight through exhaust?
The exhaust 2.25". Hi-flow cat is 2.25" in / <2.25" out (out looks like its smaller) as far as I can tell.

The catback has a 14" resonator on it. If I have it cut off and replaced w/ a 22" magnaflow resonator, will this quiet down the exhaust?

Or maybe I should get rid of the catback and go custom w/ the 22" resonator and 5"x8" 18" long muffler, which I probably should have done in the first place.

 

high flow cats dont make your car louder, youre aftermarket muffler does.

 

Not sure of the exact science of it but for some reason DC sports headers are FRKN loud! I've quite a few people tell me that once they put one of those on their car it got a lot louder.
Yeah I agree totaly that cats don't make the car louder, they smooth the tone out though.
that exhaust wasn't a turbo version was it? (sorry if this sounds like a dumb question) cause that will make your car a lot louder also.
hrrrrmmmmmm.......

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by mustanghunter &raquo;</TD></TR><TR><TD CLASS="quote">Not sure of the exact science of it but for some reason DC sports headers are FRKN loud! I've quite a few people tell me that once they put one of those on their car it got a lot louder.
Yeah I agree totaly that cats don't make the car louder, they smooth the tone out though.
that exhaust wasn't a turbo version was it? (sorry if this sounds like a dumb question) cause that will make your car a lot louder also.
hrrrrmmmmmm.......</TD></TR></TABLE>
The DC Sports Catback is p/n SCS8009. Single Cansister Exhaust for 94-99 GSR.
AFAIK it's for NA. Piping is 2.25".
The Header is DC Sports p/n AHC6607 (4-1, 1 piece).

For the time being, I'm going back to stock. Will probably sell the catback and eventually have an exhaust custom built with a long resonator and a larger muffler (DC Sports one is pretty small).

Before I uninstall it I'm going to try to record some sound clips with the catback installed and one without it (just header and hiflow cat). Just want to see the difference.