I had a Pro-M on mine. I suppose it's somewhat cam-dependent, but my meter went back to Pro-Flow twice for recalibration. At speed it was great, but the tip-in was awful. After corresponding with numerous other Mustang owners I found many similar stories, but not always. Considering that most EB's don't see much drag strip time, it doesn't seem worth the hassle. As for the cam issue, no doubt part of the problem is with cams with smaller lobe separation angles. The ECU's don't really like cams with less than 114 degrees, but my cam is at 112. The difference in streetability from the Pro-M to the stock unit was dramatic in my case.