ive never had above 91 in my ba.
only because i cant afford anything more
first year apprentice wage sucks

If it runs well on 91 why spend any more

ive got a ba xr6 N/A and i use to fill up with caltex 98, petrol prices went thro the roof and 98 turned to be 1.40+ on the cheap days, me getting the s**t with over priced fuel tried 91 e10, i noticed NO performance decrease, but fuel consumption did go up slightly 0.6l/100km. because the e10 burns quicker or something it has a affect that actually pushes the octane rating to 94-95, the new ve2 commies have the ability to run on 85% ethanol as most of you would know, running on that high percentage will increase performance to a higher level then 98 RON petrol, however on the down side the engine does run significantly hotter, and chews threw more fuel. so basically i see it as a second option to LPG just you get more power