I'm getting a bit confused about pistons. I'm sending my cylinder in to be replated to stock bore. I want to get the top end kit and don't want to wait to send the piston with the cylinder. I'm looking at getting a Pro X piston. They have three different sizes. B, C, and D which are each .01mm difference. The total from the smallest to the biggest is only .02mm or .0007". Thats a ridiculously small difference. Which one should I be getting?