your question piqued my curiosity (along with my recent reinvolvement in flying models) so i did some digging around and found this:
http://www.chem.wisc.edu/courses/901...pdb/nitro.html
if the vehicle that you are planning to fuel with nitromethane is catylist equiped then do not, under any circumstances, put any nitromethane in the fuel. here is the deal, catyletic converters (and some O2 sensors) contain paltinum, which is soulable in aquariga (50% mixture of sulphuric acid and nitric acid), and nitric acid is a combustion byproduct of nitromethane. because of this i am quite sure that burning nitromethane in a catylist equiped vehicle will poision the catyletic converter. i appoligise for raining on your new found parade.