pistons and rods would be good for when you go for high nitrous shots or forced induction. Using the stock 10:1 piston ratio you can get them forged and also stronger rods to keep the engine together for high reving and running more than 8 psi of boost in our car. I would only go with 12psi at most with 10:1, but people buy 8.6:1 or so for forced induction with a psi range over 12 and anyplace above to a point. If you plan on running a lot of hp or reving high it would be a good idea, along with valve springs, valves, sleeves, and things like that.