I found out about those a couple years ago when I did a google search for Ramchargers (that's how I found this place too). I kept finding parts listing for 98-up. One was a ram air hood with a picture, up until then I thought it was a typo or something.
I talked to someone at a Dogde dealer a couple months ago and she said they could only sell them in Mexico because they're real loose on emissions. Something about Dodge couldn't bring the emissions within limits to pass for the whole country, which just sounds like a load of crap to me, if they wanted to sell it here, they would find a way.
I saw one with Baja plates here in southern California last year. It looked real nice, especially with the custom wheels.