Ours reads differently on our test truck as well. Usually 3-5psi difference. I've noticed on the IssPro I'll hit 40psi at WOT and the Adrenaline will show 36-38psi. It could be that one is mechanical and the other is electrical. I guess some guys have a huge ordeal with how much boost their making, considering we get 5 calls a day asking why they aren't making 100,000,000psi like they were with the "other guys" module they had. 3-5psi isn't going to make that much of a difference, IMO.