I am pretty sure my cat needs replacing on my 2001 GTP, slight smell of rotten eggs every once in awhile and lurching when coming off of a long high speed expressway drive.

1. Does mt 2001 GTP have one or two cats?

2. Would getting a magnaflow cat improve my performance any, yet still be as quiet if I just replaced the cat with stock one?

3. Should I get the o2 sensors replaced as well?