What 300cc kit are you thinking of going with, MRP or polini? I have the MRP kit and it really puts out a lot of power, but like zombie mentioned I have cooling problems. I have the head at the machine shop and I'll keep you guys posted if getting the head decked fixed it. I've never heard of this before with the mrp kit so it may well be my bike not the kit. I would suggest getting the Naraku cam for the 250cc motor even before you get the kit, better bang for the buck and easy to install too. I like the x250, solid bike, really stable at high speed because it's practically the same chassis designed for 500cc.