With 12.0:1 compression and Nitrous you MUST use C-16 race fuel (VP Fuels). If not expect detonation problems regardless of the ignition timing of the engine. C-12 (112 octane) is not enough. It is not that the octane is not good enough, it is the burn rate of the fuel that will get you into trouble every time. C-16 is formulated for use on high compression Nitrous engines. I went through a very steep learning curve when it comes to high compression and Nitrous. Not one nitrous book or Nitrous manufacturer that I spoke to when I was burning up pistons and cylinder heads and gaskets, not one mentioned anything about using the right fuel. They all concentrated on ignition timing, and fuel delivery and quantity NOT quality of fuel. Every Book I read about building Nitrous engines, not one example of a Nitrous motor being built was higher than 10.5:1 compression. They all talk about the right Air/Fuel ratios to run and the right ignition retards to use, and the right plugs to use, what octane fuel to use, ect. And 112 octane is fine for a 13.5:1 compression engine, until the Nitrous hits! You may get away with using lessor fuel for a while, but it will kill your engine in the long run. After you have replaced pistons, gaskets, had cylinder heads eaten up, ect about a dozen times, it gets real old real quick. Once I made the switch to C-16, not only did the breakdowns stop, the car went .5 faster in the 1/4 mile! Best E.T. by the way was 9.76! on a 225 H.P. shot.