I dropped the compression in my RB stroker from 12.2 to 1 down to 10.3 to 1 using a Ross custom, reverse dome piston designed with the guidance of Dwayne Porter. The pistons were light to begin with at 524 grams, and the new pistons were spec'd at the exact same weight.
That being said, Smokie Yunick is said to have swapped in pistons in his race engines to suit track conditions that were nearly 100 grams different than what he pulled out of his motors with no vibration. However, all the pistons were of equal weight.
I spent the money to get them the same weight as the pistons I was replacing, as I only wanted to build the motor once time and didn't want to chance it. Turns out according to Ross, it is a bit of an engineering challenge to get those big pistons down to 524 grams, but they did it.
