Does anyone actually know if the firmware of the vehicle is different for the XLT package VS. the Platinum package in terms of allowing more HP based on octane rating? Maybe someone that works at Ford or has done dyno tests with different grades of fuel on an XLT package.
Wouldn't the following statement imply that they limit the HP boost based on which model you've purchased?:
"However, the engine does show more muscle as you reach the top of the trim level lineup. Housed on the Expedition XL, XLT or Limited, the V6 delivers 375 horsepower and 470 lb.-ft. of torque. Behind the wheel of the Expedition Platinum, drivers get boosted to 400 horsepower and 480 lb.-ft. of torque."
It sounds like if you have an XLT, you get 375HP and that's it. A higher octane would only eliminate knocking if you have experience it. If you have a platinum and run 87 you'd get 375 and running 93 would increase you to 400. Unless I'm reading it incorrectly... It's all really just a guess anyway unless someone has actual proof that the base model will allow the increased HP output.