It is so when you floor it, or just give it alot of throttle, such as pulling a hill, it will force the transmission to use a lower gear, so you are higher in the RPM range and have more power.
Also, I asked if you had a 2.0 or 2.6, because it is hard to find a header for a 2.0. The easiest way to find out if your engine is a 2.0 or 2.6, it will say on the plate that is on the radiator support (I believe that is where it is on a ram 50), if it says G63B, it is a 2.0, if it says G54B, it is a 2.6, or look at the exaust manifold, a 2.0 looks like this (Mine with a Weber 32/36), and a 2.6 looks like this (also with a Weber).
Here is a Wikipedia link
http://en.wikipedia.org/wiki/Automatic_transmission

Also when looking for a Weber, do not buy a Weber 32/36 DFAV, it is very hard to get parts and instructions for, or a Weber for a standard, get a 32/36, that is for an auto, also make sure "Weber is cast on the carb"