Thanks for this. When I was tuning my 370Z, I ran into a few guys doing the E85 routine (over at Sean Church's place).
Anyhow, E85 takes some consideration. I don't know if our fuel system is E85 ready -- is our car a "flex fuel" car? If not, that's something to sort out.
100 octane no-lead is available, but just not convenient. Back in 90s and early 2000s, I could get it from my local 76 in a pump. I recall thinking how expensive $4.50 a gallon was! I'd kill for that price now.
I really don't want a bigger turbo right now. I think part of the fun is the super fast spooling -- but I totally get that we can install a bigger turbo with superior characteristics (spool, flow, etc.). The turbo-back exhaust and down-pipe (and big cat) is good stuff and I'll probably do that.
Also, I had two WRX cars! I love them. If my dealer had a "base" STi, I might be driving that now (great deals on those right now). I had an early Cobb tune on my "265HP WRX" and it was good fun. My early 2001 WRX was more built, but frankly didn't make big power (I ran a lot of the AUS rally scene stuff).
This is a great conversation, and I'm looking forward to more on this topic. I hear that E85 is a lot easier to find, so that could be a real alternative.