I have an 89 dakota sport with a 3.9 yesterday i took the belt off the pulley for the smog pump and i gotta say my truck runs sooooo much better it a lot smoother acceleration and better over all response. It didn't set off the check engine light as i still have everything in place i live in a state that has strict emissions laws so i can't completely gut the system yet but if you have an LA series 3.9 I'd highly recommend doing it if you haven't all ready

 

doesn't that belt also run other stuff? my 90 LE does...Would like to try that...

 

mine just ran the smog pump its was super easy took like me all of 5 minutes to do