Sorry I didn't see this was in the 2nd gen forum, but anyways I run level 3 with bow boost fueling on level 3 also. It still smokes when I flog it, and seems to be about the best MPG also. Towing my trailer, I run level 2 with low boost fueling on level 1. No smoke at all.
I'd run higher levels, but I have a stock clutch!