- Mustang GT . Race Series Cat Back Removal of Stock System: Figure 1 1. Apply a penetrating lubricant liberally to all exhaust fasteners, hangers and rubber insulators. 2. Loosen both OEM clamps located at each muffler inlet, and both OEM band clamps at the H Pipe outlet. Lift the lock tab to slide the band clamp rearward. Do not discard these clamps. Refer to Figures 1 and 2. Figure 2 3. Remove the OEM over axle pipes by lowering the inlet ends and pulling them out towards the front of the car.