You pull the sleeve out of the engine and smooth all the rough edges so there like glass, and grind the exhaust port so it better matches the actual exhaust port in the block. Also on the VX engines I have found the bottom of the crank shaft has a crappy unsmoothed molding edge and it actually rubs very very very slightly on the crank case housing, so I take my connecting rod and smooth and polish it so the fuel and air can flow smoothly around the crank into the engine. In it's most basic that is what porting in polishing is you take all the rough edges and areas and make them glass smooth so the fuel and air can flow smoothly into and out of the engine. Gives a nice little power boost. Oh and buy the way, I was wrong about your exhaust you bought I hadn't noticed the smaller outlet, I wasn't paying attention, but as for the clutch bells I guess it depends on how many Hobbytowns you have competeing against each other to get a good price. There's 10 in our area so that maybe why I can get better prices at Hobbytown than I can from Tower. Anyway wanted to say sorry I appologize.