FWIW, I am still running Vishnu OTS Stage 1 v1.55b and have switched back to 91 octane after a tank of 94. IAM stayed rock solid at 1.0 throughout the tank of 94, but when I switched back to 91 it has remained pretty much at 1.0 during my logging (done after filling up a 2nd tank of 91). I saw it dip to about 0.96 at one point but it quickly went back up to 1 again and seems to be holding steady. Don't know if the 1.55 tune is just better optimized than v1.42 but it does seem to work well for me.
http://www.datazap.me/u/pmok/stage-1...log=0&data=1-7