I run dual hooker aero chambers behind my 454 and they are great I don't know why more people don't run these muffler, they have no drone , and are quiet while driving, and sound great while idling, the only time they are loud is when you are on the gas hard, really sounds awsome 3000+rpm ,no tinny sound at all , they are also made of really heavy duty construction which is perfect for offroad, they also flow better than flowmasters, even the super40, and cost less. If you want quiet all the time with alittle rumble then flows 70.