What year Miata?
Early model, 90-93 diffs, can't take alot/much of abuse at all.
94 up Torsen type diffs can take a good bit but 300hp high RPM clutch dumps will undoubtedly take a toll...as well as possibly implode the tranny.
If you seriously want a beast to hammer on then a typical approach is to utilize some drivetrain parts from a turbo Rx7...and even that has it limits.
Of course driving style and use are major factors here.