I have this installed in addition to my MSD ignition box. There is four stages you can preset and activate with the flip of a switch. You can also set the prestart setting. I think this is better because when your racing, you don't have time to trun a knob to the exact line you desire. With this, all you do it hit a switch and you get the timing you want always. I set my distrubitor at 18deg and retart it down from there. This way, I don't have to use a timing light all the time just to tune it.
Part number : 8975
