Originally Posted by Mike@N54Tuning.com
He can plug the BMS CPS module in soon and offset as much as he wants. Based on other 91 octane testing I've seen he will need to offset around 7 degrees to eliminate the drops and then will need to increase boost from 11psi to 13-14psi just to break even again on power. What he really needs is higher octane. A richer AFR will also help. High elevation + poor gas + all wheel drive does not make for great tuning potential.
For reference, another local 335xi on the same dyno put down around ~389whp IIRC with full bolt-ons & Procede, and I'm pretty sure he was running straight 91 octane (no meth). The guy put down roughly the same numbers stock as I did (both around ~280whp & both AWD). Again, same dyno:
^^^I've seen the graph at MAC (looks like it was removed from his thread), pretty smooth as well. Admittedly haven't seen the logs, but IIRC he was running Procede autotuning for reference. So there's some tuning potential, how much on an otherwise stock car remains to be seen, but won't be a mystery much longer.