At Land Speed Trials and the dragway I always use Shell 93, they do not specify the E content but it’s in there, and it varies dependent on location. Near the end of Land Speed Trials running 93, I put in some 90 non-E plus some octane booster aiming at 95 octane (in the M6). That next run was 1/2mph faster in the 1mi than the previous, and 1mph faster in the 1.5mi. Compared to the next prior run 3hr earlier it was 1/2mph slower in the 1mi but 1/2mph faster in the 1.5mi.
Obviously there are too many variables for a valid comparison, but:
1. Speeds had been consistently decreasing all day as it warmed and wind increased, and the boosted 90 changed that trend.
2. My ass feels like the higher the octane the better.
3. Comparing to the previous 2 prior runs with 93, the boosted 90 had a better acceleration between 1 and 1.5mi.