Bring as it's 2" taller than stock and .8" wider I would say a good bit.
A friend on his, 2" Leveled 13 5.0L Platinum 4X4 3.73 is running 275/65R20(34.07X10.83) Nitto Terra Grapplera and he is averaging 12.5-13. Mixed city and highway, only upgrade is Airraid Jr Intake with OEM Filter.
Another friend on his, 2" Leveled 13 5.0L Larait 4X4 3.55 is running 305/55R20(33.21X12) Toyo AT2 and he is averaging 14. 90% highway, only upgrade is Airraid Drop in Filter and Flowmaster Resonator back exhaust.
I am 2.5" Leveled 13 5.0L FX2 2WD 3.55 with 275/60R20(32.99X10.83)Nitto Terra Grapplers and I average 16-17 75% city. Upgrades are resonator delete, Airraid Jr intake with OEM filter and a tune.
They both are a little bit hard in the skinny pedal than I am also.