Keep it at 14 to 16 like HNN said.You should be fine,if everything is setup right. A main girdle,with studs wouldnt be a bad idea though. The stock forged pistons are plenty strong.They are TRW's. We have put a 225 shot on a stock block with a girdle,numerous times(Not that it's safe or that I would recomend doing that to anyone). They always lived until human error blew them up.Such as leaving the switch on,ect.