I race C class and my stock 250f is down on power and I knowingly need more. It just has a full pro circuit T4r exhaust. Other than that, it's all stock. The exhaust added power but not enough to my satisfaction. I've won 2 races and got second in 2 as well in beginner class. So moving up to novices was hard with little power. So my question is, what are some effective mods that will give me considerably noticeable power gains? I'm considering porting and polishing the head, a 270 big bore kit, air4orce intake, etc. Please leave me some advice on what I may be able to do to increase power. I don't want to buy a 250 2-stroke but I may have to if I can't get more power out of this 250f. Thanks!