I just bought a used truck that has a hypertech box in it. From what I hear from the previous owner the mechanic/owner before him put it in and increased the horsepower.

How do I get it back to normal?! It looks like an older box, I do not see any modern equipment like I see on the hypertech site. I get about 6mpg city. Not looking for specific directions but more so to head me in the right direction on how to reverse this. I am contacting hypertech too, so a non biased, non sales answer on this forum is good too.

Thanks!