MINI Madness has a lowering Spring for the R53, can anyone shed some light on these? I can't find much information or reviews about them.

 

I would look into whether or not the springs are progressive or not. I have TSW springs and they run linear in design. They are more predictable imho, but most springs are progressive for the cooper (easier to handle on the street I suppose).

I would shop around before you buy those. Look at txwerks.com the best spring I have used, had some H&R as well just didnt like the feel.