DP tuner, the other one no technical support. It's easy to reach them when you want to buy their stuff but as soon you want to have some change it's another thing. I send them a message december 21 for cold weather problems still waiting for answer. For my case i give up gonna look on SPARTAN or INNOVATIVE .
with a 7.3 don't go with spartan or innovative, go with either dptuners, di, tony wildman, they're all good... and PHP i've heard some good things... oh and gearhead automotive is another good one