Diablo has had many issues with their units.
As far as I know they are not supported at all any more and are not being made either.Bullydog was the one I think making the Diablo Sport boxes and they have stopped.....Andy
I had one on my truck a LONG time ago....didn't notice any mileage change, but I could notice a little more power. Now its on a truck out in the AZ or NM desert if I remember right, lol