I ran 3" Flowmaster mufflers on a 400 and it was way too loud at cruise but sounded great at idle. The drone that comes at speed with the flow masters is a headache to go if you have to travel very far. I saw a FB recently at the dragstrip run a 11 flat 1/4 mile with 2.25" factory style pipes and a cross flow type muffler in the stock location. It makes me rethink running super load pipes for performance.