Oh man...whatever you do to the tip of a muffler is no substitute for proper exhaust tuning. The "turbine" requires kenetic energy from the exhaust pulses to be spun, and in this way create backpressure. Exhaust gases will need to slow before tor turbine, what happens when kenetic energy must be transferred from one medium to another. This is where backpressure is created by this design. Because of this energy transfer and the amount of heat involved...did anyone imagine what would happen if the turbine were to become jammed?????