don't spray through the i/c, it will freeze and break letting the coolant into the engine, go direct port, taping the manifold runners will be cheaper than a nozzles kit. i'm able to use a smaller pulley with n20 because the i/c effect reduces k/r, i run a 3.4 most times and a 3" when spraying at the track, if you remove the i/c you can use a t/b spacer and a single nozzle kit. i'd still have to say n2o is the cheaper way. yeah over the long run the cost will eventually cross over, but your not spending the cash all at one time and it would take several years before that happens, a 100 shot can be set up for about $800, and will run the same as someone with headers, cam, pcm, i/c, and ported blower, plus the n2o car will have the advantage of being stock for emisons testing, better gas milage and everyday reliability, but the powers there when you want it, how offten do you run the car hard anyway, less than 1% of the time for me