Any differences at all? I know having a hollowed out cat gives a more rhasphy tone to the exhaust.

 

Your best bet, especially living in CA, is to go with a nice, high flow cat. Most here agree that the Car Sound is one of the best, especially for the money. I think the flow rate is almost double that of the factory. Mike at IPS or Dave at SMSP can better answer your questions.

 

A test pipe will have no restriction at all , a hollowed cat has a small inlet and small outlet which will still not be as efficient as the test pipe. Being that you are in Califorinia you need a cat. Test pipes are for offroad use only.

 

Thanks do you know if there is a big restriction with the hollowed out cat. considering the convex shape of a cat?

 

anyone have the number or website to smsp. Thanks