OFT stg 2 UEL 91 vs 93 - noticeable difference?
 

Price difference aside from the different fuel grade, is there a noticeable difference between the two use of the two maps and fuel grade?

My BRZ has OFH + OFT only. Otherwise bone stock everywhere else. (plans for Billet Power Blocks soon!)

I just have the stage 1 but the 93 tune had a noticeable difference. Might as well empty your tank and fill with 93, then flash stage 2 93 to find out. At most it will be 3-4$ more, it's worth trying and you can be the judge whether it's worth it or a change has happened. It won't hurt your engine at all, I only run 93 and it gets better MPG and feels faster.

Only difference between 91/93 tunes is about 1.5 degrees extra ignition advance over 5000rpm in the 93 tune compared to 91 tune.

Maybe worth less than 5hp.

however running 93 fuel will generally result is smoother performance/feel and less knock in the lower rpm ranges (1500-3500rpm) than 91 fuel this can sometimes result in your IAM dropping slightly from 1 to maybe 0.9 on 91 fuel even on 91 tune. It will be much less knock than on standard factory tune though, not going to do any harm.

If 93 is available its worth the extra.