[mrmax]

There is a profound difference. Pipe diameter is 2 1/4 inches inside quieter pipes. Inlet is offset to one side. Very restrictive. Took mine off and cut them apart. Also gained just under 80 horsepower, similar torque. with a K. Craft 428. Did a sound comparison to Connecticut standards. (used to live 8 miles away from era) The classic chambered 3" with packing was only 4 decibels louder at 3000 rpm. higher revs the difference is even smaller. up to you do you more of the power you paid to make or your hearing.