2. Being that it is a Bassani set up, I think their cats would come as sort of a "High flow" type cat, so I wouldn't think it would be much of a restriction. Unless it had 100,000 miles on it and they were clogged up or something.
i just did the opposite with stock catted h pipes. took off the bbk h pipe and put on the factory part. not a big difference in sound. flowmaster 40 series out back and i believe they are the deciding factor on how loud it is.