2006 V8 w/18k on the motor. 2.5" lift w/Donahoe CO front and hoe springs and shocks rear, 265/65/17 stock tires, SW sliders, front hitch, Volant CAI and Gibson exhaust. Oh yeah, and one new windshield wiper.
Everything else stock.
I was getting 17 with the CAI only. Added the Gibson catback and it went up to about 17.5. Then I stopped using the Lucas gas additive and it jumped up to 18.8 on my last tank.
I milk the gas for mileage and most of my commute is a backed up freeway. I got 20 on my trip back from Tahoe and that was before the Gibson and I was using the Lucas additive.