That's going to somewhat depend on what gears you're starting out from, as well as how much fuel economy you're willing to sacrifice in order to win back acceleration. You also need to make sure that your truck actually has a 9.75" rear end, as most 2015-2020 2.7L F150s have Super 8.8" rear ends. In general, 4.11s and a custom tune should still get you decent performance and acceleration. However, you may want to jump to 4.56s if you are going to run 37" tall tires. Give us a call directly at 623-434-5277 so we can get more specific about what you're going for and what rear end your truck is equipped with.