boring is kinda tricky at first, its kindaof a backwards process. you can order your thirty over pistons from rockymountainatv.com with out knowing the metric equivalent. and that the first thing you need to do. once you receive them youll notice a number stamped into the crown, this is the pistons actual size, and thats what size the cylinders need to be bored too. if you just have them bored to .030 its likely that the pistons will vary slightly in size making the machine work useless. i hope that makes sense, if not ill try to clarify.