My input shaft doesn't have the groove milled into it, this is where they commonly fail as it's the weakest point of the shaft.
Since the wall is thicker and there isn't a groove in it, the strength of the shaft is greatly increased.
To retain lockup, PI milled a groove into the hub of the converter, which sees no stress.
They put a seal in there and it functions normally.
So basically way stronger input shaft, no loss of TCC lockup.