MBHD
My down pipe is 4" about 24" long for racing, for street a 4" pipe and a 4" dynomax muffler to the rear end, if I want to carry on a conversation in the car I cap the 4" pipe after the muffler and a 3" pipe exits past the left rear tire. Working on a system that will open the 4" pipe automatically when is goes to boost.
Harry
