The 04 in my sig is the truck in question...right now it is running without the smarty. The truck seems to fall on its face with a trailer hooked up, it runs pretty quick empty, but even then sometimes it takes forever to get going. Its like a gamble on whether its going to take off or limp away...its not awful just noticeable. With a trailer its rough...i tow around 19000lbs and the truck seems to move it well in the low gears, but sucks it up in the higher gears. Also, this truck can run to 1250 stock....even more with a trailer....what the freak gives? Any ideas?