they may be heavy but they also wont deform or flat out break for nothing these have lived thru cracked cylinderwals,droped valves and even ben run with a serious collant loss and the pistons are still fine
I believe it. I've been running TRW forged pistons on my 340 for 8 years now, and since they came with the engine who knows how long before that? Several thousand street miles, several hundred dragstrip passes, several over-revs, and they are fine.