New HD f150 with the lightning engine in them (minus IIRC 30hp) do 13.9-14.1. Not slow at all. You would just be sacraficing a good looking and handeling truck for some extra room. I personally don't like the HD external appearence, but the interior is very nice.

95 SE Modded - Gone 98 E0 Black SVT - Gone 98 se sport - Broken 00 T-Red SVT - Nice