What about an (E92) M3 GTR?
On the same note as the CSL (M-Division modified, official) what about a M3 GTR?
Back in 2002-2003 Schnitzer Racing needed a more powerful M3 for use in races, especially on the Nurburgring. So they made a M3 with a V8 (like in the new 550i (E60))
What I might be getting at is what if they took the V10 from the M5 and M6 put it into the E92 M3 and have themselves a modern GTR. The old GTR has 400lb/ft at stratospheric revs and about 50 more horses than the stock M3.
CSL is unbelievably awesome but GTR still wins any day!