Thanks for info Jack. My Gryphon, Speedo, and GPS all read the same at 60mph (the GPS is an aftermarket Garmin and is not connected to the truck's speedo). I was assuming the original pcm file had the stock tire size/wheel size info already programmed, and the Gryphon built on that file. I haven't played with the custom tuning options. I'm going to let Bill do that for me. If I don't know what I'm doing
I'm afraid I might damage something :scream: I agree with you about the rev limiter. I bet that is the issue. I'll recheck it after I get the custom tunes.
Mark