@TiGeo, haven't looked at DataZap logs in a while, but the E is definately helping out. I saw no KR with the E blend. Fueling has some headroom as the HPFP is basically flatline so you could bump up the E content some and still be good. The E would help the spool speed down low with the big snail too. The plain 93 is killing the midrange with all the KR @ 4K. It's sending panic attack alerts to the wastegate to dump boost in an attempt to stop the knock. Who's tune are you on? I did Cobb/EQT with their E30 and on the IS20 it ripped. If I had done an Autotech HPFP mod, I could run straight E85 without MPI or bigger LPFP. YMMV with IS38 though.
And for advertised octane readings with regard to Flex Fuel, they have to label the MINIMUM octane acheived with the minimum amount of E. In this case 51%, but obviously higher with higher E content. Local stations that are rock solid ~85% year round advertise 106 octane on the pump. Should be right as I've tested fuel several times and always ~85%, which I also verified with my Fuel-it! reader/app. Plus, the state's Dept. of Agriculture is ALWAYS testing fuel in this area just to keep the spot fuel buyers honest.