Very cool van!
A 4" turbo-back exhaust and new intake should drop your EGTs pretty well. I know a couple companies that make it for your van for under $400 (aluminized). "Full Boar Exhaust" is one and "Diamond Eye Performance" is another.
You can do-it-yourself a "Tymar" or "NAPA 6637" intake on the van. Check the diesel sites like powerstrokenation and powerstroke.org, etc and you'll get an idea of what's involved. You will have to get creative with tubing bends to fit it under the hood. You could use 4" ID aluminum tubing with rubber gaskets at the bends or 4" ID PVC piping.
I can't find it at the moment, but I know I saw pics of someone who put an intercooler into a 7.3 van. They used a 6.0 superduty intercooler and had to relocate both batteries and the radiator, so it took some doing.
All three of these should decrease your EGTs and improve your mileage.
Keep us posted! I for one am very interested.
__________________
www.VibrantLED.com -- '02 7.3L Excursion Limited ~135Kmi total; ~50Kmi on WVO
Vegistroke V3 (installed 4/09); HIH, Aux Pump, FPHE (added 11/10); WVO Designs CF
PHP Gryphon; 6637 intake; 4" exhaust; Terminator HPOP; Tru-Cool; Evans NPG+; other goodies...