X2 on the aeroturbine, I have a 3" dp that runs into the 4040xl. As stated before when you run 3" it's obnoxiously loud and IMO doesn't sound that great. The "xl" model has a built in resonator gives it a nice deep tone, straight thru design and under acceleration the ol' girl has a nice bark. Before this muffler I was convinced that I would never get a meaty sound out of the truck without a different turbo and downpipe. Look em' up. You'd need the "3030" or "3030xl" if you wanted the built in resonator. They're amazing mufflers. I took the torch to my bully dog muffler bc it was too freaking quiet.