If you still want to try restricting the BCM outlet tubes, do not ruin the muffler by pinching one of the tubes. I simply plugged one of the tubes with a gob of JB Weld which can be drilled out and removed easily or drilled out to a size that provides just the right amount of muffler pressure for your engine. I am now running a ST 2300 with one outlet plugged with JB Weld and then drilled out to 1/4 inch for perfect running.......RJ