Super HP-2 Muffler 409SS - 2.50 Center In./ 2.50 Center Out - Aggressive SoundFlowmaster has taken the laminar core of our classic HP 2 muffler and wrapped it in a new compact square case. The new Super HP 2 Series muffler offers the same great performance benefits and moderate tone that you would expect from our laminar flow mufflers, now in a new sleek styling. These mufflers are available in either a 409S stainless steel case or a polishable 304S stainless steel case and in sizes ranging from 2. 00 in., 2. 25 in. and 2. 50