Drilling holes has never been so nerveracking. But this modification that anybody can do to their stock muffler is simple and effective for a motorcycle, especially at higher elevations. I will be adding an EJK fuel controller to smooth out the motor, revs, powerband, decel, throttling, etc. I will ride with these six 3/16" holes for a week or two and see how I like it and how the bike performs. I may widen those holes slightly to a 5/16 or even 3/8th of an inch for deeper tone and more air flow at this 6,200' elevation.