The M8 engine has various pros versus the prior Twin Cam engine, however there are a few cons that have surfaced such as the low idle note combined with a choked stock exhaust system that doesn't allow the sound most are used to. S&S Cycle has heard the customers and created the GNX slip-on mufflers. This pair of mufflers combine a 4.5" muffler body equipped with a tuned baffle and finished off with their race inspired end cap, letting the sound and power flow as it should. Black finish matches OEM heat shields dB reducer installed but can be removed Unique louvered baffle Fits with 13.5" rear shocks