Save your money and make it yourself for track days. We call this "Rocket Fuel".

These are based on LA prices

10 gallons of 91 octane @ $3.45
1 gallon of Toluene, 115 octane @ $6.50
1 gallon of Xylene, 112 octane @ $6.50
1 gallon of Klotz Coxoc, oxygenator @ $22.00

Final octane level is somewhere in the range of 102 and only costs you $5.34 a gallon.

With an OEM ECU, you run the risk of the timing being retarded to offset the fuel, but it works great with ECU maps that advance the timing. Especially good for forced induction engines.