What he have here is a comparison of a custom IPS spec JE pistons designed for endurance racing and a "stock" off the shelf , regular JE piston.
The shelf JE piston specs:
J.E. 13.1:1 (87mm)
weighed 334.5 grams
its wristpin weighed 97.9 grams.
The IPS spec JE piston (endurance racing...