So i have a 04 coupe and have the current mods
JWT intake, Z tube, Spacer, and Greddy Evo2, now the flex pipe on the evo2 broke so i welded a new one in and it no longer leaks.

now i put Random Tech HFCs and the car rasps quite badly.

someone told me it was the mufflers, but i've no idea.
please help

if worst comes to worst i'll buy new hfcs

 

It was me, I put a kazoo in your muffler tips while you weren't looking.

 

Many people have rasp problems after modding their cats. A resonated X pipe from Magnaflow helps with toning down the rasp and you pick up some low end torque too.

Need to figure out if you have 2.5 or 2.25 pipe and pick accordingly.

 

Add in some resonators.

 

^ the exhaust has 3 resonators i believe.


my question more so is, is it the brand of cats i have, or my exhaust?

 

Dig the Z forum. They have been combating rasp on the greddy and xo2 systems for some time now. Resonated X pipe. It's your cats. But they've been combating rasp associated with running test pipes. But same idea.

 

Tape dem bitches up or get em ceramic coated. End-o-rasp.

 

wat?

 

Wrap the test pipes and Y pipe in heat tape. It deadens raspy sounds.

Ceramic coating does the same thing, it's just more expensive.

Both of those also help with heat, no need for heat shields when you're done.

 

^ really i'll give that shot soon.

will that also lower the noise from the exhaust? i don't want it quieter by any means.

 

I've been having troubles searching stuff, that and i'm lazy and only tried once

anyhow i have a Greddy Evo2 exhaust i want FI hfcs,

anyone else have that setup? i need to get rid of this rasp, it's driving me insane!
i still can't figure out what's rasping i don't to replace my cats only to realize it's my exhaust

thanks for all the previous help guys