All of the "+20 horsepower" mods you see on E-Bay and the rest of the internet are total crap. They use the phrase "UP TO" to get away with it, although I think any of them who call it a 'chip' should be drawn and quartered.
The kit consists of a five cent resistor you can buy at Radio Shack. The rest of the packaging is designed to hide the fact that it's a five cent resistor that they bought from Radio Shack. Your engine's IAT sensor tells the computer what temperature the air is running into the engine, and the PCM does a little bit of tweaking to the air/fuel mixture. The resistor/kit overrides the IAT sensor and forces the computer to think that the air is colder than it really is. You will never, never, ever see anywhere near 20hp from this modification, and I'll bet that 99% of these scamming idiots probably have absolutely no clue what resistor values produce what temperature settings for a Dodge Dakota to begin with, they could be shipping you a product which sets the air temperature at 300 degrees.
Relocate you IAT to your cold air intake, this will do the same thing, cept it will still be measuring an actual air temp. this will make the truck run slightly richer and slightly more timming. More torque, less HP unless you have airflow mods to need the extra fuel.