Do yourself a favor and throw that piece of junk in the garbage. That is known as a, "piggy back" tuner. All claims that those guys made all those years ago have been proven to be inaccurate and a lie. It will not benefit you at all sadly. Maybe in the first 5 minutes of driving you might notice a difference but your PCM will learn its way around it in short order and you'll be right back to stock.
I have never used one myself so I can't help you in the install, I just remember those hours of fighting and arguing on forums way back then haha.
It is always better to go to a standalone-flashable hand held tuner. But, being that you have a 2003, the options are very limited in what you can actually achieve.
