need a little help here from nx kit guys

[stanggt00]

i got an msd rpm window modulator for my nx kit set up and just need to know one thing were does the signal wire from the modulator hook up to on the motor

its has 5 wires

black wire GROUND
red wire POWER
yellow wire HOOKS UP TO YOUR GROUND SIDE OF YOUR NOS SOLINODS
gray wire (NC)
white wire (signal wire ) <----- it would hook up to a tach if i had one but i dont and its said u dont need

instructions on this thing sucks not detailed enuff for me



any help would be great thxs

we have coil packs on each spark plug so do i just hook it up to the number #1 piston spark plug ground or am i still missing something