I have .030 off my head, opened the exhaust port up 1mm widened it 2mm per side; on the intake I rounded the corners by approx 2mm, a 28mm slide carb, blaster reeds with the stops cut off, Banshee pipe, and am running 130 grams of weight in my Comet 94c clutch. I topped out at 37.6 mph and at that speed it sounded like the engine was going to explode. I run a solid 33 mph without over revving the motor.
Its a lot of work but I can't get in the water this time of year so I have to do something else. At 37 mph its really squirrely and I wouldn't recommend it. If you have a stock clutch you will not be able to take advantage of the pipe unless you know about tuning primary clutches. I don't think you can get different weights for a factory clutch and soon you won't be able to find them for the Comet since they went out of business. I posted pics of the Banshee exhaust here
http://www.buggiesgonewild.com/gas-y...sugestion.html