I machined from aluminum billet a db killer for a Mistral slip-on for my 11' Griso. I wasn't happy with the sound from the modified one that I got with the used Mistral so I figured why not make one. What I have is a conical shape 1" at the small end with a 7degree taper and overall length of 4" on the outside. The inside is .875 at the small end and is stepped up from there with 24, .250 dia holes allowing the gasses to flow through. I milled the holes at a 30 degree angle to the taper thinking it will flow better. I was able to try it on a 10 mile ride with mixed results. It needs a little more sound and it may not run as strong from a seat of the pants feel. I'm going to do some more to it, such as open the holes up that are closer to the big end and see what happens. I'm looking for opinions here from all. Thanks,Scott