I spent some time looking at this, it seems al the work has been done in the USA, where most of the motors went, fitted into X5 trucks, 545s, 750s, etc.
I found, but lost, a site offering a supercharger to fit into the V, replacing all the inlet stuff and offering +100bhp and +100 ft lbs.
Without traction control I think that increase, especially the torque, might make the cars a bit of a handful!
