well..
some rb25 pistons take a beating some dont
my car only just clicked over 40,000 klm from new, i was pumping 13 psi into it with AFR of around 11
and one good rev - power slide around a corner and, that was it.
lost compression in no 6 from 155 down to 55.
stripped the motor and i actualy had 4 pistons with cracked ringlands
the rings were still intact on all 6 cylinders, and the car was still making good power, just ruff at idle
so you make up your own mind..
thrash it till it blows, or build it properly from the start and enjoy 20psi and 300 - 350 kws for years to come.