I just bought a left over 5.9 Dually Mega and I want to buy a tuner. I've read that the Smarty doesn't leave a trace for warranty issues. I'm under warranty obviously and I don't want a tuner to ruin that if possible. I've heard good things about Quadzilla as well. I could use some advise here guys...I put a Superchips Tuner on my 7.3 Powerstroke and now it not only doesn't read when I plug it in but it's stuck in Tow Performance mode. At least that truck is outta warranty. Any ideas?