I ran FM's when they first came out on my 78Z, they were big but you didn't hear them till you opened it up. So big they would bite the ground on the back edge of the case and eventually busted the seam. Went to the 40's kit on my 80Z and have been debating changing them for 2 years. If you don't have a cross over I would try that first then if it's still to loud find something else. Pypes has just introduced a new set of turbo mufflers and I'm looking at them. Running Hedman mid's and 2 ¹/²" pipes. I need to have the pipes re-routed to clear the 2004r crossmember but just been to busy to get it done.