mileage. the harder i try the worse it gets...

318 recent stock valve job with head resurface. factory 273 4bbl intake with NEW eddy 600 performer 1 inch open spacer. small lunati cam 458 lift [email protected] duration 110/106 center line. new stock electronic ignition. factory manifolds with dual 2.5 piped with cherry bomb extremes exit under rear bumper. factory 2?? gears 7.25 rear. stock size 14 inch rally wheels. no matter how i drive it i cant seem to get more than 11mpgs. what gives. too high gear maybe? mostly drivin in country back roads of foot hills of nc. runs great good power and the exhaust is not strong. its killing my pocket.:sad7: