I've got a Supertrapp disc setup that I purchased brand new off Ebay last year. Installation was a breeze, took two wrenches and a hacksaw, plus about 30 minutes. I run mine with all the discs installed (loud as possible) and haven't gotten any complaints. It's loud, but not annoyingly so. Cost about $100, plus shipping, and I'd definatly recommend it. Currently I've got a K&N filter installed with stock jets and the needle clip set in the middle. I'll have to fiddle with it when I put the new 33mm carbs on, I'm sure.