I've got a 2000 integra ls-t, ive got a thermal true 3 inch sitting in my shed and im thinking about puttin in a test pipe and losing my cat....would this give me a significant hp gain? is it worth it?

 

Yes it will help, but only like a few extra ponies, maybe 10. Also you exhaust will become super f*cking loud, I would'nt recommend a strainght pipe for NA, but the turbocharged community will benefit from it. So ahead and do it, the worst thing that happens it that you replace it with the cat.

 

I've got a hallowed out cat right now (a result of trouble shooting. A clogged cat wasn't the problem. ) and it didn't make my turbo D any louder.

I'm going to make a 2.5" test pipe this weekend and see how it works out at the track this Sunday.