I have the Phantom Autometer tach with a shift light, and you can dial the shift light at any desired rpm to turn on. In my opinion it looks nice at night in the car, but brings too much attention and I wish it was a tad smaller.. The Pro-Shift Light can be used independently without an Autometer tach, and those rpm module pill things are plugged in at pre-set increments instead of dialing in (not as precise, but does the job as well). It plugs into your rpm-out signal from your ECU wire. The smaller gauges built to replace A-pillars are for rpm, Air/fuel mix, exhaust gas temp, oil temp, fuel pressure etc... You decide what you want. Those gauges have nothing to do with the modules.