Oh yes. You want to shave down the flywheel. I was balancing one of my flywheels that had already been milled down, and just to see how good of a job I did, I mounted it in the chuck of my dremel and slowly spun it up. Took me by great suprize how much air was being moved even with it milled down. A full flywheel must rob TONS of power, like 500-700 rpm I'd bet. The carb that Peter offers would be a good idea as well but if you want to spin large dia. props stay with the stock carb. You want high rpm go with the larger carb. If you try a larger carb than what my ryobi came with (walbro) and then swing a 18-8 or a 20 something prop, the air vilocity through the carb is becoming to low to work well and your better off to use the stock carb. The reverse is true if you whant to use say a 16-8 or 16-10 and go for rpm, put a large bore carb on and dont fall into the prop.lol Peters mufflers are the best I've seen for our use. The #1 reason is that his pipes screw in to the muffler. Think about it, no one elses pipes are like this. This allows me to make to small holes in my cub cowl, place it on the plane and then just stick the pipes up through the holes to screw to the muffler. Nice clean install. No huge gash nearly the length of the cowl to slide over welded pipes. In most caces his mufflers are cheaper. Hope this helped. Mike.