I don't know much about nitrous but though that it would be a good combination. I've read that the nitrous reduces the inlet air tempature. I would suggest a wet kit and you might want a seperate fuel cell for the nitrous. That way you don't have to worry about the varying fuel pressure of a returnless system and you get exactly the right mix of fuel and nitrous.
I am gonna retune with the meth and maybe a smaller pulley. I was curious if anyone has ran nitrous with meth injection cause both have the effect of cooling down the intake charge. I know i can run alot more aggressive tune with the meth now.
I would not try running them together at least to begin with. I have no experience with both at the same time but I would think the extremely cold phase changing nitrous may condense or freeze the meth and/or water.
You have not told us the details of your engine and tune. I can run a lot more boost, timing, and spray than a higher compression engine with smaller cams both with the same octane.