If I put pr3 pistons on my ls rods does that mean Im going to have to get them re balanced?And what kind of cost am I looking at for a re-hone to 81.25?

rods and pistons arent balanced like a tire or a flywheel. if your just getting new pistons the term "balancing" them would mean making them all weigh the same. this can be accomplished by taking large numbers of the same parts and pairing up the ones that weigh the same or by machining the heaviest ones to weigh less. its not something thats necissary but its not a bad idea. to put it into perspective, a factory motor's pistons dont come balanced.

as far as the cost of a rehone your going to have to ask your local machine shop.

I dont know to much about rebalancing but I thinks its good.I got my rods balanced but not the pistons and I got the crank balanced

And honing I think is like 60bucks

should run you $125 to do .25 over