These results are very similar to what BMS hit with their F10 M5 which was 678 wheel horsepower using methanol injection although in 5th gear on a Dynojet. For now it seems the best bet for big power is a piggyback tune increasing boost with meth injection as an added safety mechanism to prevent detonation.
It will be interesting to see how E85 benefits the S63TU as well as tuning evolves on the platform but if the N54 serves as precedent turbocharged and direct injected BMW motors love the cylinder cooling and octane benefits of ethanol and methanol.
Dynograph below using a 50/50 mix of methanol to distilled water on 93 octane. This is the same M6 that went 11.0 @ 128 in the 1/4 mile recently:
Baseline before meth injection: