Hey guys I sold my buddy one of those mileage max chips from edge. Here is the problem before putting it on he was getting 14 mph, he puts it on and gets 18 mph for the first tank then it drops to 16 then to 15. It smokes like a freight train even with the cat on. Oh, yeah it is an 04.5 with the six speed 315 and an aem intake. The dealer suggests a bad injector what do you all think. And forgot to mention he pulled the edge back off and is now still at 14mph.

 

My bet is the placebo effect.

He was expecting better mileage right after the install so he drove easier on it for the first tank (consciously or not). Then as the tanks went through it he slowly went back to his previous driving habits, plus the cool factor of the now increased smoke = only 1mpg better.