91OCT is the problem our cars are best @ 93+E. If you add 2 gallons of E85 to get a ~ 91/E25 blend you will be ~93 and will pickup more power with more timing added. I run E30 with 91 and can tell the difrence if i drop to E22. 91 is shit gas.
Just did a back to back two day track day on my stock tires then my 4s and ran faster on a hotter track/day on the 4s. Times where almost identical but overall speed was slower on the second hotter day. Granted tires are not the same size 305/30 275/30. This was also my first time on track with...