(This is for my Civic, but I'm putting it into a tC's perspective. All the other forums I've posted this on aren't helping.)

Basically, my setup is:
OEM Header > OEM S-Pipe > 2.5" Midpipe w/ 18" Resonator > Tsudo Axleback

It gets loud once it passes 4k, and I already have a RandomTech high flow cat sitting around. Would installing the cat before the resonator quiet it down?

 

Minimally.

/end thread

 

Are you positive?

 

95% positive. The purpose of the cat isn't to quite an exhaust down. Especially a high flow cat. You'd be better off with a good resonator or 2.

 

Okay, then explain this. Why does a tC instantly sound better with the OEM header on?

 

It may not be a cats purpose but it definitely plays a role in keeping the exhaust quiet.

 

^ That makes much more sense.
I would get a resonator, but I already have a RandomTech cat sitting around. I just want to be sure that it'll actually quiet it down, so I don't waste money on having it installed.

 

yeah i dont want to wast money anymore... i paid almost 800 dollars so far for my custom exhaust...

i bought the car with megan racing header...

then i bought an HKS muffler and full custom 2.5 piping from s pipe. and a 24 inch magnaflow resonator


The system was ok then the sound changed completely and started to fart a lot lot more. so i thought the resonator gone bad or something so now i order something else.. Aero 25 resonator but i also ordered a megan racing s pipe...

so now i have Megan header, Megan S Pipe, custom mid pipe with 1 AR25 resonator and custom axle back hks muffler

the car is louder than before thanks to the s pipe but the new resonator didnt help at all. now i want to know what should i do.. another resonator or hi-flow cat.

i wanted to get a cat since the resonators are more straight thru than a cat.

 

I put a magnaflow resonator on my old bimmer after I had the exhaust done( I replaced the cat with a high flow version because it actually deteriorated and plugged up my exhaust)...it helped TREMENDOUSLY.

Before It was horribly raspy, and after it was perfect. Nice and mellow, no more rasp. I know you probably don't want to put magnaflow on your megan setup...but...it worked very well for me, and was cheap.

http://focus.c-f-m.com/magnaflow225o...resonator.aspx

 

Not so much when speaking of a high flow cat however. Length and flow are what resonators uses to quite an exhaust. Most high flow cats are very very small, and it has very little internals to it. It really won't make a difference imo.

 

You need to look into mangnaflow resonators,possibly two of them, it will change the sound dramatically

 

I've done both on my TC Magnaflow cat and magnaflow resonator. I found the cat to make the exhaust much quieter than the resonator.

 

did you get them in the same time?

 

Okay, turns out using a cat as a resonator is more toxic than using only one cat (for a Civic atleast).
If you want to quiet down the car, USE A RESONATOR, OR REPLACE THE MUFFLER. Pretty much the end of the story there.

 

i had a civic from the same generation that you have, and i had a full header back exhaust on it, just straight not resonators or anything. Well, i used to live in PA and i had to pass inspection so i had a OBX high flow CAT installed and it did quiet it down... but only a little bit took away a little rasp as well.