OK here's the setup
GSR Motor
Stock Header
2.5" Invidia Test Pipe
2.5" catback with a twelve inch resonator
And a turbo muffler with a turndown at the end (its hiden up under the bumper).

So after putting th invidia test pipe on I'm getting a really raspy sound at about 3k rpm to 4.4k rpm.

Should I hollow out the stock cat and have that act as my test pipe/extra resonator?

 

You should've tried getting a high flow cat from Magnaflow or something to that effect.

There's nothing in there to baffle the sound, maybe another resonator?

 

I definitly don't want to plug it back up. My car feels so much better like this.

 

Hmmmm

Maybe just have the performance and deal with the noise?

Or maybe going to an aftermarket header to even out flow? I'm not too sure on the collector size for the GSR header

 

Get a bigger resonator. If you have a 12" get an 18"

or go for a high flow cat.

 

Sweet. I will switch out the resonator this week and let you know. Thanks.

 

Megan racing sells a test pipe resonated. Thats what i use so it won't rasp.

 

Thank you. I will try hollowing out the stock cat and see if that works out before i buy another test pipe

 

A test pipe will do that. Changing the header isnt gonna help much either. You need to go with a highflow cat or a resonator only problem is both of those will restrict flow. Its a catch 22 more flow = louder Quieter= less flow.

 

I will try hollowing out the cat and if that doesn't work I will get a bigger/another resonator. I'll let you all know how it works out.