Sorry to tell you that the CAT dealer is the only one that can reprogram that computer. You can't get any more HP unless you pay for it. Their computers are linked to CAT corporate and it tells on them if they bump the HP. CAT will then bill the dealer for the difference in cost and they will in turn bill you. They are pretty friendly about setting all the other parameters the way you want.
You can set the cruise control to kick the speed up when it drops 1, 2, 5 mph, etc. The Jake brake can be set to come on automatically in cruise when the speed increases as well. They will remove the speed limit for you. Talk to your local CAT service center and they should help you out. If the truck is new, they usually don't charge for the initial setup. At least that's how our dealer works.