Nitrogen is cheap compared to trying to dry your AIR going into your gun. Every compressor I have looked at including my GX Cs2 has a single point of air intake that is filtered to keep crud out of the compressor just use that as the intake port for the Nitrogen . Feed it from a standard industrial tank does NOT have to be 6k or 4.5k get a fairly cheap regulator for a local welding supply store some hose and fittings to match the inlet on compressor. 1/4" hose at 10 psi going in keeps up with compressor easy. little side note nitrogen has 0.01 ppm of moisture @-70c. A tank that holds 120cubic feet of N2 will fill your guns for alot more than 4000 shots. a cubic foot of n2 =28316 cubic centimeters n2.
I have a marauder that has a 210cc tank at 2900psi thats about 2 cubic feet at atmospheric pressure thats from empty(I never empty it) about half so I get 50 shots per fill about 120 fills sounds like 6000 shots on a 20 dollar (gas only) bottle, regulator and hose should be less than 100 bucks, tank rent 12 bucks a month or less or just buy an exchange tank from the welding supply store anywhere from 100-200 bucks no rent.
Terry