its an M45 supercharger your talking about
you will need to lower the compression ratio to around 8.4:1 if your going to run the standard pulley

you can either do this with low comp pistons or using a decompression plate

the cheapest method is the decomp plate you can get these from ferriday engineering (ferriday.co.uk)
also are you planning on using the bypass system that the mini uses? or just blank up the hole in the inlet of the supercharger?