I posted this on another thread, but I'll expand on it here. I maxed out boost and timing on 94 octane right around 16psi and 16*. When Sunoco stopped selling 94, I had to drop to 15psi and 15* unless I dumped in a can of Lucas octane booster, which let me go back to 16/16. When I went to the track and mixed in some 104 (about 50/50 mix), I ran about 17psi, but I lowered timing to 14*, and only got one good run in, which still had a couple blips of KR. I'd guess I might have gone to 17/16 at the most.
Switching to E85, I am now running 18psi and 18* of timing every day. I have had boost as high as 22psi, but I ran out of injector just over 20psi, so fuel delivery is the only thing holding me back now (this is on 65# injectors - hope to get some 80#'s soon). I really doubt I could get anywhere near this much power on meth injection, and I know it would be no where as easy to tune as E85. I literally drove to the station, filled with e85, adjusted the IFR table, and was good to go. I have tweaked the IFR table once or twice since then because of ethanol blends from other stations, but other than that, I have not touched anything in the MAF or PE tables.