yeah there is a changeover point where you peak 5v on the stock GTR afms and need to upgrade
the problem is it's a costly exercise so a lot of tuners have been able to strech the curve a bit
when you max them there is no harm done, it just means it cant show any more resolution
this means you dont use anymore load cells on the tune
if you max them at 6000rpm not a big deal
if you max them at 3200rpm a big deal and it ends up being a map sensor tune
when i say a map sensor tune, i mean the load axis never changes once you reach target boost
as map sensor is on pressure and boost is fixed by wastegate / boost controller