I have heard from numerious people that the 6.5 is near its factory tolerance limits off the line. However, its safe to do things like 50hp upgrade and about 80ft lbs. Beyond that the longevity of the motor drops drastically. I see things like +190hp upgrades etc, how safe are these? Assuming you have a fresh motor? For those who have one, how many miles do you have on these types of upgrades?