Ok so when I bought my 89 mustang gt it already had an off road h or x pipe, im not really sure. Well I wanted to get slp exhuast, but I want to keep the cats OFF. When I do end up buying the slp exhuast, is it going to come with a cat or what? Or can I just install it without the cat or do I just keep the x pipe on or what? Haha im so confused, I dont want to buy the wrong thing!