Read the details below from @Terry@BMS:
Got our 2011 135i back on the dyno today to rebaseline with the new dynojet software and verify the latest BEF changes. As most already know the new winpep8 software absolutely blows. Mods on the car include JB4, MHD BEF, Pure Stage2 turbo, Fuel-IT port injection rail, BMS intake & CP, HFC, and a generic intercooler.
Anyway, I did a little tuning on 91 octane for kicks but didn't find anything that worked much better than the PUMP BEF combined with map1 @ 16psi. For these runs I set the PI values all to 0 to disable it. Timing cleaned up a bit at 14psi but power was a lot lower and still had some drops. Dropping timing further didn't really help much and also dropped power. Enriching AFR didn't improve things and started to tax the fuel system. Tuning is always about finding a compromise between various factors and with crap 91 octane, this is about as much as I'd want to push this specific setup.
Later in the testing I added ~40% E85 and retested map1 on the E85 PI BEF, which runs a little more timing, adjusted fuel scalars. And it picked up nicely.
Finally towards the end I did a couple runs at 22psi which seemed to be the sweet spot for balancing timing and boost at least today.
Higher boost N55 tuning can be a bit of an enigma at times but we're slowly making progress with the platform.
Also did a lot of other testing in between these runs and made more power but these three curves represent what I consider "stable" setups you should be able to run down the half mile with no issues.