I installed the new Petronix ignition system on my 1974 280C which I received from Retro Rockets. If anyone is considering this swap I would highly recommend it. During the process I also installed a new coil with a 1.8 ohm ballast resistor. Prior to the switch the car seemed to surge slightly at 60 mph and it also seemed like the engine really labored when the transmission went to shift between 2nd and 3rd gear. It almost felt like the transmission was slipping. After installing the ignition module and coil it has much more power, the surging is gone, and it powers right through second gear to third. I also disconnected the vacuum advance. I'm running 7 degrees initial advance which gives me 38 degrees total. The entire project took about 1 hour.