The phantom grip is a locker differential. It is a small metal block that is spring loaded to lock you diff when necessary. It does not work 100% like a LSD but has a similar effect on traction. The problem with its power handling capability is that it still uses the stock diff and is actually trying to lock metal against metal which can create a lot of friction. The more power it has to hold, the harder it has to work. I am sure the power ratings given though is to cover their own ass if something happens and the diff explodes more than saying that at that exact rating your diff will automatically fail. Greg is using a phantom grip on his 99GS running 15psi making 282fwhp so far and has not reported anything wrong. Well at least not last time I heard from him. That has been a couple of months now. Personally, I do not trust the stock diff and like the idea of a true LSD. That is just me though. I have a quaife.