Power Tune XTO Insert Kit Includes two each of the 1.375", 1.5", 1.625", 1.75" plugged front with 3.5mm holes, 1.75" plugged rear with 3.5mm holes, 1.875", 2", 2.25", and one 1.75" plugged, Tunable inserts allow for easy sound and power adjustment, Power and torque tuning, Tone and sound adjustment, Easy to install
