every one is being unfriendly about this so here goes. The easiest way to do this and to be a little on the causious side is: Cut the face of the baffles off with a dremel. If you do not have a dremel, open the holes up as much as you can in the front of the baffles. If you have a dremel and can, cut the baffles out. Do not cut the outer box of the muffler though. Next, on the right hand side of the muffler (as you are looking at it) on the side wall, drill out (4) 3/8" holes in a square pattern and a small 1/8" hole in the center of these to put a screw through for putting a screen in. When you get the holes in the side and the screen in then you need to build a little deflector to weld on the side so that the hot exhaust gases are pushed forward and do not melt your break handle. If you do not do this it will melt it in half in short order. Or if you would like to have it done; I dual port mufflers for $18 per muffler.