Size does Matter!
The 89-93 stock M90 has the smallest inlet size to the blower, so therefor can't pull enough air, so the SC cavitates, and builds heat very quickly. No amount of snow injection or intercooler size really helps because the blower is just so inefficient with such a small inlet to the back of the SC rotors.
This is only one reason and other will probably chime in other reasons.
94-95 SC's had a little better SC inlet opening and performed better with an same amount of OD, but still can't go crazy on those until it has been ported.
Smitty