its that the oem pistons will fail before the stock rods...therefore you dont need aftermarket rods unless you have aftermarket pistons.

if you use the new rods on the oem pistons and spray too much the pistons will fail. if you use stock rods and stock pistons and spray too much the pistons will still fail. either way your weak point will be the oem pistons, so the upgraded rods are useless.

im done, if you dont understand that i have no idea how to explain it to you.