do not do the flowmasters your self. they are charging about 50-75 for install, that's worth it. the flowmasters are very big mufflers and are a pain to install, and they are very likely to rattle, bc they rub on the rear most hangers, rear most bolt. and they also tend not to line up perfect without some adjustment to the over axle pipe, rotating it a bit. but do get these mufflers, the sound is worth it, and bc of the baffle design (i.e. not fiberglass packing) the sound will NEVER change.