Tuners almost universally void warranties, and the dealer can tell even if you return it to stock. My attitude is Ford engineers spent millions upon millions of dollars tuning for a balance of power, economy, and performance. The only benefit to tuning comes from simultaneously removing emissions, another warranty voiding action. Resale on tuned trucks is also quite a bit less. I wouldn't even consider it unless I was out of warranty, *needed* more power, and was willing to suffer the motor and transmissions consequences.
