I'm gonna cut off my tailpipes tonight and put on some turndowns. What size turndowns and clamps do I need for my stock 2.25" tailpipes? The guy at Advanced Auto Parts said I would need the next size up, which is 2.5" so they would fit over the 2.25" pipes, but I noticed that they flared out on the end, so do I need 2.25" i.d. turndowns and u-clamps?