The AFE Stage 2 uses an adapter the attaches to the lower airbox, using the stock clips on the lower box. The air filter goes through the new metal upper part of the airbox. It seals against the bottom of the hood. It uses the stock intakes in the lower box and fender. The only thing I didn't like was the overall fitment of it. It was VERY tight! Certain parts didn't line up exactly right. I even sent pictures to AFE, and they were baffled. But, I got everything to fit. I think it was just a manufacturing fubar that day. The part I don't like about the AFE setup is that when you take out all of the old O.E. resonance tubing, there are a few wiring looms that are held by the resonance setup and AFE made no provisions for these wires to be secured to anything. Thus zip ties and a little bit of fabricating. But other than that, I really like the setup. It added a nice kick to the low end. Wish you the best of luck deciding.
2011 F-250, XLT, 4x4, 6.2, SWB, 3.73's, Stage 2 AFE Intake, Catback Flowmater, 5 Start Tuner.
Semper Spes, Numquam Quieti