Engineered to handle todays higher displacement motors, upstarts feature 1 ¾” head pipes stepped up to 2 ½“ quadradical up-slash muffler bodies.Internally, stainless steel, perforated core baffles wrapped in dual density packing complete the system.Full coverage 2 ¼ “ head pipe heat shields, 18mm o2 ports with 12mm inserts, and hand crafted, high quality fit and finish round out the package.