I've posted on here multiple times. With no success. So I've decided to do what I never really felt comfortable doing. I'm taking the Z to a shop. I recently thought the cats were stopped up so I cut off the main cats and never put them back on and the pre cats were hulled out by me. Should I try to put the exhaust back on, as in will it make a difference when I take it to the shop in the performance of the car?