look down inside your exhaust ports and you will see a hump in the top corner of the port, that is for air injection, there is also a hole in the end of the head for it too. i couldnt tell you what the difference between those heads and the D0OE heads like i have is...sorry, kinda new to sbf myself.
hope i was of help though
Daniel J. Ludwig
I\'m the blood on your guitar
I\'m that wave you caught back in 1975
I\'m as strong as a thousand armies
I\'m as soft as pedal on a long stem rose
I am love~Social Distortion