[Jackpine]

Jared, it sounds like the Gryphon is fine. If your battery dies, there's no reason at all to reset the truck's tune to stock. Just unplug the Gryphon before jump-starting the truck (to minimize any chance of damage due to voltage surges) and then you can plug it back in once the engine has started (it can be plugged in with the engine running, just don't try to tune it with the engine running).

Now, if you can change the tunes, there's nothing wrong with the Gryphon. I cannot explain why the truck seems less "powerful" though. Possibly, the dead battery has caused it to reset to the "stock" throttle position mapping. (You still have the same power, it's just that you have to press the pedal down further to get it. If this is the case, the PCM may "relearn" the throttle opening rate you prefer.)

That may also explain what seems to be low gas mileage too. Are you using the MPG readout on the Gryphon or are you calculating it using gallons to fill the tank and miles driven? And, during the tune switching, are you sure you have the correct settings for Gear Ratio and Tire Size? An error in those can effect shift points and mileage readouts.

- Jack