pretty much the same thing... i think the ZEX wide open throttle activation is through measuring the volt reading from the throttle position to the ECU, vs. the NX activation is mechanical i think (i.e. when the throttle body is wide open it engages)...
i guess go for what color you like best... the ZEX could maybe be more "accurate" since it works slightly different with the whole wide open throttle mechanism...
I got the ZEX because i want it to stand out, and i think it looks the best... i also got a good deal on it :3_chubby: