Originally Posted by MGYVER
These are VERY expensive engines to work on.
As far as I know there is no ready made kit for supercharging or turbocharging these engines.
If you have to rebuild one you're probably looking at over $10,000 easily, plus you need to find someone who CAN rebuild it. Markus Glarner would probably be the only one who could do it locally (T.O.). and properly.
Albrex made a sc kit for the 3.8l m5.
There are other people who can rebuild it properly and in less than a year.