[snowman]

It ain't quit that simple either. You must be concerned with TWO weights, the rotating, and the reciprocating. In the case of matching weights of opposing cylinders, you would match just the reciprocating. The reciprocating is composed of the small end of the rod, plus the piston and all its components.

YOu need to learn about all these things BEFORE you go about doing anything that changes your engine. If you do not you may do more harm than good. They are not difficullt to learn and a couple of days with a good book is all that is usually needed. I would suggest a book like "engine blueprinting". All the same things apply for a Porsche.