Spock my man, The Service DVD says use a Ridge Reamer to remove built-up carbon or the piston ring lands may be damaged. Cast Piston alloy is relatively soft and damages easily. Those pistons are about 250US a pop. I would highly recommend buying the original repair dvd as it is an indispensable tool and filled with trouble-shooting guides, torque values, special tool part#'s, ect. I shutter at the thought of doing major engine overhaul without it. Good luck!