DHP has not been supported by the manufacturer for years, and it is my understanding that you need to know a lot more about tuning to use it vs something like HPTuners.
If you have not added any mods, and your fuel trims are normal, then I would not mess with it, and even if you have added some mods, trying to tune the car without knowing what you are doing will most likely end in you destroying your engine.
For around 100.00 to 150.00 you should be able to get somebody that tunes for a living to do it.
I'd suggest finding some books on tuning, and learn a good bit before even considering to do it yourself.
Not sure how much it will help you learn about tuning, but here is the manual for DHP, it wouldn't hurt to read it.