Does anyone know of a good ECM type devise to control my fuel mixture on my 502 Magnum w/ a ProCharger? I was told the regulator I currently have is junk and the only right way to do it was with a computer.

You need to send your dyno sheet or engine specs and the ECU out to get recalibrated. Several companies/people can do this - Arizona, Whipple, and others will do it for $300.

or

http://www.perfmarine.net/

If you want it done on a dyno.