Just recently ordered a Glowshift 7 color LED tach from Amazon. Actual info on installation was hard to come by, but got it done. I used one of wires off of one of the coil over plug. Use the wire that is unique color for each plug. The other wires continue the same color from plug to plug. It doesn’t matter which plug/coil you use. Just know that you have to set the tach to “1” cylinder for it to read out correctly. Rest of installation is by the book. I’m lovin’ it. Best upgrade I’ve done yet.