Pro Racer Package. It is tuning software for the computer that is a nice addition to the XCAL 2. The XCAL only allows you to tune the basic things with the car (things that most people want to tune)...look at what you can do at
www.brenspeed.com it has a list of things that you can adjust. If you decide you want to adjust more than whats available on the xcal2, and you want to be able to adjust about everything, then you need the PRP as well. The Xcal2 normally costs $300-$400 and the PRP software is around $300. To upload the tune from the PRP, and use it on your car, you need the Xcal2. So your optons are...
Buy the XCAL2 (limited tuning capabilities)$300-400
Buy the xcal2 + PRP (can tune about everything)$600-700
*EDIT*
If you have to ask, you shouldn't be tuning without a lot of research on the topic. Call up Brent at brenspeed and talk to him, and he can tell you exactly what you need.
