I am considering porting my head when i do a hi comp piston. Ive read alot on the subject and feel confident in doing so now. I rebuilt my old 22R and did this on it with mild improvements. Although now after researching, i found i only half finished that port job! My question is, has any one used XR'S Only for this service? If so, what was the cost? What was the improvement? Now i realize a couple key points are, 1: Smoothing the short side radius. 2: keeping a semi rough wall surface(INT.), and mirror finish(EXH.). 3: Dont port match the EXH. port. 4: Smoothing the guide boss. How do i add "Swirl" to this head? Any other thoughts?