Read it again slower. The +2mm stroke has nothing to do with what piston to run. If it is a long rod or stock length does deterimine what piston you have to run. If you read it says. 4mill Long rod crank, and a stock stroke long rod crank both require Wiseco 795 series pistons. What deterimes the series of pistons run is determined by the rod lenght, not the stroke.
Hot Rods #4001 Stock stroke, stock rod lenght = 513 Series Pistons
Hot Rods doesnt make a +4mill stock rod crank any more. There are others that still do. = 513 Series Pistons and one of the following (cut stock head, cool head with cut stroker domes, spacer plate under the cylinders, spacer plate between the cylinders and head).
Hot Rods #4011 Stock stroke 5mm long rod crank = 795 Series Pistons
Hot Rods #4105 +4mill Stroke 5mm long rod crank = 795 Series Pistons and one of the following ( cut stock head, cool head with stroker domes, spacer plate under the cylinders, spacer plate between the cylinders and head)
So the determining factor on what series of pistons you need to order is the Rod Length, not the stroke.