I have had a MegaSquirt MS3 Pro on the 68 Barracuda for nearly 5 years. I did all of the installation and the tuning. It has been 100% solid.
Concerning the comment about voltages, nothing difficult to accommodate to anyone familiar with wiring in relays. And yes the main grounds for the ecu and the air fuel meter need to go to the battery ground side.
As the FI system controls both the fuel and ignition side, I like having the ability to change the fuel map or ignition curve with a few key strokes on a lap top. The MS3 Pro also includes the ability to control electric engine fans, has a two step limiter, can interface with electronic transmissions to enable a unique ignition curve for each transmission gear, has a self tuning feature and has the ability to data log.
Are after market FI systems for everyone? If you have good computer-electronic-mechanical skills and you understand the basic FI principles, it is just another feature of your car.
If you want your car to have the traditional fuel and ignition systems or are not comfortable with FI systems, you are probably better off staying with a carb.
