Good luck cant wait to see it done! Id make the diffuser black give it some contrast but thats just me, I have a white car and love the black and white. As far as an 04+ front end, deff not my style but it can be done probably not worth the time IMO though. They put 10-14 front ends on 05-09 Mustangs, you have to mock up the fenders a bit to fit the body lines but anythings possible.