Tachometer help

i just bought a tachometer for my car but it has a seperately mounted ignition coil. The instructions say to mounte it on the negative on the coil but there are 4 wires that split into 2 clips that plug into the coil.

There are 2 wires on one clip that are black. The other clip has 2 wires that are grey.

Do i have to splice the wires on the clips that clip onto the coil? and if i do which ones do i splice.

Thanks in advance for your help

Danny