For what it's worth I have a weir kit fitted to my supra diff and it's mounted in a kit on a standard rear beam.
I had 530hp and the car was used in anger (2wd) and saw some drag action too.
I split the original cover almost straight away but the MT billet cover I have has been faultless so far.
I will be upping the power another 150hp next year so we'll see how it handles that.
I will try slicks at the strip too next year.
I also have a spare supra diff with a different ratio in it incase I ever wanna swap
Cheers Paul