Thats a tough one.
I'd be looking at using a lube instead of octane booster though, LPG is between 100-110 octane I think.
Don't know about nitro and LPG though, but you only want the stuff for either strip or show, not much use on the streets unless you want to spend a bit of dosh each time you want to get to the speed limit as fast as possible.
xtaxi would be the one to ask.