The only problem with the otherwise better wet paper is that it's hard to find in a grit larger than 220. Apackage of the better dry papers of 150 or 100 grit will work. The 150 actually has more cutting points per square inch. Stroke the head about four times in one direction and then four at 90 degrees from there, etc etc. It will go faster that way. If you want to go beyond the fins like I do it's easier to take a big file just to the fin sections to wack em down so you are not laboring sanding the fins too. A compression test of 200 psi is 13.6 to 1. I go up to 230. The stock piston is strong and can handle it