If your street setup (440/500 HP/TQ) utilizes meth injection and keeps temps ~ 265, why the need to reduce power back to stock levels? From what I remember you have a Procede right? To go back down to 300 HP, are you going to run the methanol map (4) at something like 8psi in order to try get to your desired 250 track temp level? At 8psi, the meth wouldn't give you any extra power but perhaps it could keep oil temps down and prevent limp.
Daily: 2013 e92 M3 MW FR DCT ZCP / ESS VT2 650 S/C, MRF mid/Akra slip, ST BBK
Track/Airstrip: 2011 997.2 Turbo S PDK / GIAC tuned / Ohlins coils+LCAs+endlinks setup by BBI Autosport
Beater: 2013 X5 3.5sport