NPD suggests measuring the ring at the position it sits at TDC. Ring fitment is done with the torque plate installed as well.
Once everything is balanced, we also measured out the rings for the proper end gap. This is also done with the torque plate installed on the block. The generally accepted way to do this is by pushing the rings halfway down to ensure that they're as straight as possible, but NPD suggests measuring the rings at where they'll sit at TDC. This is where the most pressure is forced against the rings and where ring seal is the most critical. The ring end gap is opened up to the manufacturer's specifications. NPD pistons are made of 4032 aluminum instead of 2618, consisting of higher silicon content. Since the expansion rate is lower on a 4032 piston, we can close up the ring gap. This will decrease the overall amount of blow by we get and burn much less oil; commonly experienced with forged pistons.