From VP Web Site
C10 is the best non-oxygenated unleaded racing gasoline available. It meets ASTM D-439 standard specifications for automotive gasoline and is legal for use on the streets. C10 is not oxygenated, does not contain any metal compounds and will not harm catalytic converters or oxygen sensors. C10 Race Fuel has been used by national champions in SCCA and IMSA stock classes.
• Color: Clear
• Unleaded
• Motor Octane: 96
• Research Octane: 104 / R+M/2: 100.
Note: The reference to non-oxygenated fuel. You can get Unleaded fuel with higher motor octane, but it is oxygenated. I have used both the VP 103 and the Sunoco GT+ unleaded fuel. With my appication and in the hot summer days, The Sunoco works best for me.
On the street I use 100% GT+ and I run 24 psig of boost with high timing.
Deep Enough
Donald McMullin