I had a set on my eighty five with a 454. They were so loud I took them off. When I got out of the car my ears were ringing. I put a set of Dynomax VT's on it but they are not much better. I have the transmission out right now, and I think I will undercoat the floor pan, maybe that will help some. I have a set of super 44's on my mercury with a 383. I haven't started the engine yet, but the inside of the car will be well insulated.