Still using the RXT... went back to dealer who built car and their Roush Tech diagnosed bad plugs... replaced with new... they compared the live data with two other new builds and my car ran identical... they test drove for at least 40 miles and no issue... shipped back to me... after another 100 easy miles, believe me, I am soo careful I drive the car like a baby, then boom, on my highway drive home, check engine back on. I just parked it in the garage... felt like a punch to the gut because after two dealerships, Mutiple communication to McLeod, Roush and American Muscle, I am over $5000 in and still coming up short... contacted delearship where I bought it and they have been golden... told they will work on a resolution...