You need to understand that exhaust when HOT has a
large volume(area)... most SB can use a 3 1/2" collector
but as you go down stream the exhaust cools and reduces
in volume(area) and the cooler the exhaust is the
easier it is to control the sound... the farther back
you put the muffler the better off you are... if you
notice that the new Hemi cars the mufflers are at
the back bumper.. we did that for power, sound and
the reduction of back pressure