I have a set on my pickup and they make the engine sound a lot meaner than it really is + if you run the pipes out the back they are pretty decent as far as interior noise goes.
There is a muffler flow chart somewhere on the net, but I can't find it. The Hooker Max Flow and some of the Borla mufflers were at the top of the list. The Aero Chamber scored well too IIRC.
