Honestly pistons wont do **** all .. for more power these enginesalready have 11.1 comp.
U want power about 140 more
Do a stage 2 texas speed cam
L86 intake and th
Shorty pipes (long tubes if u intend on the fu cat back)
Cai
And maybe a tru dual cat back
And a tune after its all done. Get an hp tuners unlocked ecu and tcm and they can calibrate ur engine and seriously have real engine power. Some 5.3 can put out over 500 if u have the right combo .... rich holender has a tin of dyno oroven setups . This engine is a serkus engine already for a stock set up. #1 thing u need is an unlocked ecu. Pistons are fine unless u plan on a 150 shot other wise forged flpistins hust break the budget. U can do all that above for under 4 if u shop smart and do most all irself minus the tune.