The Purpose Of 1.6 Rockers

IT all about lift and adjustability. 1.5 versus 1.6 is about .030 differance. That's how much more the valve will open in the head. Adjustability helps even out every thing from chamber to chamber. Say you are running a 508 lift cam with 292 duration. With 1.6 rockers you now have a 538 lift cam with 292 duration. Remember geometry changes a little too.
Good luck,
Mike