NewDuc,
I am with you, use only as much octane as needed to pervent knock, the rest cost you power.
From www.vpracingfuels.com/vp_01_fuels.html
U4TM
Used in stock and modified 4-stroke applications, as well as stock 2-strokes. Makes up to 6% more power than pump gas and any basic nonoxygenated racing fuel. Passes fuel rules for AMA amateur racing, and is also perfect for club level racing, CCS, WERA and AFM.