Im about to re-do my exhaust on my DD civic with an ls/v.

The current set up is a 4-1 header, 2.25 piping to a 18 in resonator to a greddy muffler.


Im swapping the muffler to a vibrant flat black , my question is if I add a cat down stream of the header will it make a large difference in noise ?

I do not have emmision testing where i live so thats not a factor.

worth it to add the cat or not ?!?

Thanks!

 

why run a cat if you don't need emissions? I say run test pipe.

 

my cat actually made a good difference in the volume of my exhaust. It was quieter with the cat than with a resonator. a good high flow cat won't hurt your performance by a noticeable amount either.

 

If your worried about sound then keep the greddy...

 

Wanna sell the muffler? is it a SP?

 

the cat will def. help quiet it down

 

buy a apexi ws2 exhaust makes a world of difference just installed this on my coupe and its quiet at idle and anything below 4k after that it's got a nice deep exhaust note but not too loud

 

run a silencer in the pipe

 

ws2 exhaust and test pipe together sound amazing.

 

I own a Greddy EVO2. He'd waste money on this swap and get the same exact ending. I get the same action with my EVO2.

 

im not sure what style greddy muffler it is, but its got to go the tip is just to damn big.

Im not saying my current exhaust set up is too loud for my liking but while im swapping the muffler if adding a cat in line will quiet things down even more then im going to do so as well.

 

honestly dude a cat makes a HUGE difference in a straight through exhaust. Don't buy a name brand exhaust they are overpriced in my opinion. And don't bother with a muffler type exhaust like the ws2 its not straight through. straight through = best performance. The resonator + cat will make all the difference in the world. Just install a 2.25" high flow cat. If thats still not enough you can always install a bigger resonator or a different style.

On my crx /w GSR swap I am running 2.5" piping all the way with 4-1 header, 2.5 high flow cat, 24" high quality resonator, and 2.5" Magnaflow oval straight through muffler. I can barely hear the exhaust even in vtec. Its way quieter than my greddy evo ever was

 

Thanks for the info , looks like im going to order the vibrant flat black muffler and magnaflow 2.25 cat today. Worst case scenario im out like $80 for the cat.