Fuel Mileage on your Hemi swap?

I am running a 6.1 in my Demon and with the Tremec T60 if I am cruising on highway I am just north of 25mpg, blasting around town driving stupid I can still get 22! Basically stock engine with headers, CAI and Holley for fuel mgmt. making well over 400hp at tire, I would have to look at my dyno sheets but I think I was at 450 at tire?