Uses stock mounting system Formed flange fits stock gasket Contour uses stock springs & bolts 6% RWHP Increase Same sound level as stock at idle and 1 - 2 db over Stock at 3000 RPM with improved (Deeper) tone All stainless construction 18 mm O2 Fitting in Inlet Pipe with Reducer Bushing for 12 mm O2 allows for installation of aftermarket devices with 18 mm O2's. MUFFLER RZR 900XP SS