Elevation has a big effect on the amount of smoke. My 05 smokes with or without a tuner. I live at 6200'. Below 3000' no smoke. The tuner is good for a couple of mpg's and makes more power. I recently switched back to an Edge EZ from a Smarty. I run a little larger injectors, and a cam. With this combo the smarty over fuels at low rpm. No smoke with the Edge until you put your foot into it. This results in the best mpg's. Yesterday I drove from Elko NV to Reno. Hand calculated 17.6. That's doing 75 to 80 mph. Before the mods I would get about 15.5 on the same trip.