Yeah the M90 is an odd choice for the 4.2. I just found that out the other day and was surprised they didn't use the M112. I assumed that since they were just going for very light pressure boost (5psi I think) that the M90 was enough. Personally, I'd just spin the M112 slower.
I picked up an S4 TVS supercharger the other day to have a play with that on the V8 but unfortunately it is far too short. I was working on the same theory as PES used I think - the TVS can make 500hp on a 3.0, so it should make 500hp on a 4.2 right? Problem is, its so short it would need to sit on such a big spacer it would poke out of the bonnet / hood. Not a good look for a D2
Plus, being designed for an FSI engine, the TVS is far too wide for the port-injected engines anyway so it'll probably just be office art!
The Jaguar / Range Rover M112 is probably the best one to use, sitting in the V with a chargecooler on the top. Loads of custom fab work though, and the big Eatons are expensive over here. Too expensive to buy on a whim just to see anyway. A screw charger from an AMG would be even better, but they are silly money. Maybe when all my other projects are done
