[Garfield]

SCCA Solo II Stock allows any change in the suspension FROM THE FACTORY. The SSP is perfectly legal, even as an afterthought, since it's a stand-alone option. So if you got a pre-spec Cooper without SSP and wanted to add it later, it would still be legal because it's offered as a separate option. This situation is run into all the time with wheels as well. If it's not part of a package, you can upgrade it alone.

According to some literature somewhere else I read, and the MINI mechanic I now race with, the SSP is bars AND springs, but not shocks. There is still some question of whether the rear bar is any bigger, I'll have to research that some more by checking the part numbers.

In the meantime, if you're running Solo II Stock, definitely get the SSP. The funny part is that you may end up going with the standard suspension front bar to eliminate some understeer. But so far, I've been able to balance the car based on tire pressures alone.