putting new forged pistons in will it hurt performance with out balancing it with the crank i know it will gain performance with balancing but will hurt it

it should still run like it did with the stock pistons

 

always balance everything...reason being, the slite gamble that one of the pistons is off, or wrist pins even, will not be worth it when you motor shakes itself apart...after a years werth of 8K+. get it all weighed (pistons, con-rods, wrist pins, etc) and balanced to 10K...why not.