I was able to break 323+whp and 417+wtq with a stage 1 flash thanks to a GSR Tune. I have no mods and running 91oct.
I've been reporting my recent results here:
http://f10.5post.com/forums/showthread.php?p=17923343
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535i MIssion Performance, PS2, Helix HPFP Kit, Wagner FMIC, Spec 3 clutch, Steel SMF, Wolf Racing CP, UUC SSK, GFB dv, SprintBooster, Custom Dynomax Exhaust, M5 Sways, Eibach OE Springs, Koni Sports Adjustable, Custom Short Ram CAI
IG: @bmwdoubles