I have a 2013 Mustang GT 5.0 manual etc. I run nitrous - a 125hp shot at 6,000 feet in elevation. I have been trying to get SCT and/or American Muscle to provide a stock tune with user adjustable parameters like global timing retard, WOT timing retard, rear axle ratio, tire size etc. They tried, bless em, but no joy. So have gone to HP tuners and their MVI 2 with 2 credits for my car. Having never done this before I have 2 tunes, one with 1 degree retard, the other with 4 degrees retard, in both MBT and Borderline spark tables, a 7500 rpm redline that the car actually runs up to, corrected rear end gearing and tire size. To get this all working takes a few more parameter adjusts in fuel rpm shutoff and torque maintenance than I am going to bore you with but the HP tune route worked great for me. American Muscle did refund my Tunes for Life purchase with no fuss I must say. BTW, all datalogged to assure working as planned.
