Nitro cools down your engine....without it your car will overheat after a few seconds. These 2 stroke engines are air cooled.....which explains those large head sinks. The head sinks and the sinks on the engine's case cannot cool down the engine alone...that is why there are nitro in model fuel. So obviously with higher nitro content you can go faster...meaning you can lean the carb more than usual. Another thing that you have to watch out for is the shim head clearance in your headsink.....you need to add more shims if you go to a higher nitro content........another thing is your glowplug.....obviously with a higher nitro content your engine needs a colder plug than the usual. Review your engine manual for head clearance (shimming).....if that's your next question. And get a good quality colder plug like an RB, Novarossi, OS, & McCoy.