Why in the world would you want to use a cetane improver? You don't want this. The fact that nitro reduces the ignition temp and creates detonation problems is an UNDESIRABLE property. You model engine ignites the fuel with a glow plug that reacts with methanol, you don't want to improve cetane and have it go off from the heat of compression. Nitro improves idle and transition because if you use pure nitro you can actually burn it with no air, or in other words it is a monoporpelent. Even the ideal air mixture ratio is about half that for methanol. This means that it will run well when very rich, which means the carb or your tuning can be less precise and still have good results. If you improve the cetane you may have to lower the compression ratio. When you lower the compression ration with nitro it allows you to use a more advanced timing (hotter plug) or higher ratios of nitro, which means more power. You won't have this advantage with those nitrates. I suggest you read the following link on racing fuels as many model sites don't go into detail, or simply has stupid made up stuff on it.

http://www.turbofast.com.au/racefuel.html

Also read this link which contains everything but nitroethane, the only sutible substitute I know of, but I don't think it works well without some nitromethane.

http://www.turbofast.com.au/racefuel.html