http://www.greddy.com/img/PHP/products/pdf/685.pdf
Pretty simple, even if you don't have the optional turbo timer harness.
One question I have for anyone who's installed this in a s14 with the factory anti-theft device... on the ignition harness there are 6 wires coming from the back of the ignition switch, but on the optional turbo timer harness only 5 of the possible 6 connections are pinned out. I am assuming the 6th one has something to do with the anti-theft device (have not taken the time to borrow a friends multimeter to check the power from each wire yet)? I think I am just going to get a couple pins and some wire from radio shack and just complete the circuit for the 6th pin, but does anyone know for sure if the 6th wire is for the anti-theft?