Originally Posted by Wade....

How are you fighting them? Sounds like a serious lack of traction to me... polished floors?

My MINI racing experience is all on indoor high grip carpet. The initial struggle on this surface is a car with too much entry steering and traction rolling issues. Eliminating rear droop and ensuring zero bump steer solves most guys initial issues. Never forget to CA your front tires side walls too.

As far as your diffs... I have run open diffs all the way to very thick oil filled.
In your situation I would think it 'safer' to run the stock open diff. With a lack of traction a thick oil filled diff could make your car a handful.

And also, ask the fast guys what they are doing. I should hope they would be very helpful getting you up to pace.

I hope that helps.