Originally Posted by MouseFink
Avoid light weight pistons if you plan on driving the car daily and on the street. The lighter weight pistons are usually designed for low tension, thin (1/16") top and second rings which will not last in a street driven engine and sometimes require .006" - .010" cylinder wall clearances. Light weight pistons with thin low tension rings are for racing engines that are only thrashed on weekends. If that is what you have, go for it.
High performance street driven engines use forged pistons that will accept standard tension 5/64" top and second rings and a 3/16" oil ring with .002" - .0035" cylinder wall clearance. Most lightweight pistons are also designed for floating pins, then you must have your rods bushed. You should never use cast pistons of any kind in a high performance engine. Stock pistons are hypereutectic (12% silicon alloy) cast aluminum pistons and are designed for tight cylinder wall clearances to reduce pollution and are quiet running for the knock sensors that are on computer controlled vehicles.
Ok, very helpful information, thanks for that