I got a 2003 Mustang Gt with light mods(Mac Cold Air Intake, Professional Products 75T.B. & Plenum combo & duel flows). I was wondering how it was possible if posssible to swap the 2V heads out for 4Vs and have it bored from a 281 to a 302 and still be passable for smog. Im sort of new to all of this and any advice would be kindly welcomed. Also, would swapping out the stock 3.27 gears for 3.73s make a big difference?