Don from Tasca here, I will post in the new members section as well. To answer the question about "how the tune affects the off-road modes". Our engine calibration has no effect on that seeing as how we don’t make any changes to the transmission or TCM, ABS system or turn off any factory torque switches, fuel controls or safety switches like most after market companies do. We simply make changes to your MAF Transfer Function, Fuel injectors, fuel pressure along with some timing and knock sensor changes. This truck drives like stock except when you stab the throttle! Feel free to email or visit our wbesite for more info (Raptor info will be up soon) www.tascamodshop.com