Interesting! I'm doing a trip of a similar length, going from west coast toward the east. See my thread on the trip asking similar "what should I do to prepare" questions here:
http://ecomodder.com/forum/showthrea...ero-21172.html
I've been told the TDIs like cool air, so I don't block off my intercooler. I suppose if the air temps were really cold, then it wouldn't hurt to block it off, but I haven't. I do block off nearly all of the grill with the exception of the lowest part; you can see a pic of it in my thread above. (it ain't purdy, but it works)
I've seen a thread on this forum from a guy that has created a 205*F thermostat for the TDI; search for threads started by josh8loop. I haven't had a chance to try that yet, but I do notice that my temps don't get up all that high even with the grill blocks so it's something I want to try out.
My Jetta also has the t4 injectors from Franko6
I'm pretty happy with them. I did install a taller 5th (0.681 I think) which helps, but I think I should have gone taller. With the current setup I get about 60mpg at 65mph.