Is the '09 Cervelo P2 Dura Ace supposed to have 7800 or 7900 derailleurs? The pictures on the site show 7900, but the bike I just bought the wife came with 7800.
Might sound dumb, but did you get a closeout or late model '08 P2C?
The reason I ask is the '09 model is officially called “P2”.
If you’re sure you got the 09, I can look into it for you. I’m heading to my former employer’s shop today for some parts 
They’re coming built with 7800.
It’s the red and silver '09.