Not bad at all bro! That Stock baseline is about right with current mods on MAP 0. your assumption, 280 whp is what I have seen for a Stock 335i on Dyno Jet @ STD correction factor.
Gear?
EDIT:
just out of curiosity, what was your air supply setup? Did you have hood open with booster fans on Intake and FMIC? without the proper setup, I was getting 160+ IATs between pulls. So I had the tech. give me better fan setup.
