lol 51 F? You can run lean with too much e85, When it gets cold out starting can be tough. N54s arent the happiest idling engines to begin with imo. I dont think youll have trouble with a modest mix, are you tuned for it?
E88 N54 Alpinweiss/Coral Red/Motiv HTA 3586r Tial .82AR/Other stuff...652WHP
F30 N55 XDrive EBII