Well I'm no expert, but I'll help you out as much as I can. As for not returning your vehicle to stock before trying a new tune, not a problem, from what I've been told (Vivian from DJ's) it want hurt a thing. When I bought my xcal 2 I went to SCT's website and updated the firmware, then I downloaded the live load so that the custom tunes could be installed. As far as unlocking your box you only want to do that if you take your truck into the dealership for a reflash or if you sell/give your box away. The xcal 2 can be unlocked 5 times, after the 5th time it has to be sent back to SCT. Hope this helps..