S&S Cycle SS550-1032 Power Tune XTO SxS Muffler Tuning Insert Dealer KitThe Power Tune XTO Insert kit was developed for tuning power and sound. The dealer kit includes two each of the 1. 375in., 1. 5in., 1. 625in., 1. 75in. plugged front with 3. 5mm holes, 1. 75in. plugged rear with 3. 5mm holes, 1. 875in., 2in., 2. 25in. and one 1. 75in. plugged. This allows the exhaust to be perfectly tuned, both sound and power. Features & Benefits * Tunable inserts allow for easy sound and power adjustment * Power and torque tuning *