It’s a couple lbs, not enough to retard timing. I can look again in the morning. Honestly, if it was my log, id pay the $$ for a custom tune to get it dialed. Is it gonna hurt anything? Doesn’t look like it. Still conservative boost. It’s enough where I might check for a boost leak. No charge...
I wouldn't advise everyone to do that. I'm a risk-taker, especially with things I can just replace with money. In my mind, worst case the car blew up and I'd rebuild it.
Meth can be used as an octane supplement, yes. Race-car race cars often run on pure methanol (e.g. M1) instead of gasoline. There are some dangers, though. (uneven distribution/atomization for example). I use meth in my build at the moment (link in signature). I was safely running E40 with Meth...