Very interesting. I don't claim to know much about EGR, but I thought I remembered reading about its cooling effects on the combustion process reducing emissions... let me look that up. Here's the Wikipedia page on EGR:
Exhaust gas recirculation - Wikipedia, the free encyclopedia
I hate to put a downer on your idea, but with the pressure on companies to improve fuel efficiency and the fact that EGR systems are already in use, you would think any potential efficiency gains through EGR would have been thoroughly explored by now, no?
The one thing you may/may not have going for you is the use of post catalytic converter and cooled exhaust gasses. Most EGR systems operate by taking exhaust before the converter where it is still full of pollutants and is very hot. Your tailpipe extraction, plumbing it all the way back to the front of the vehicle, will mean it is "clean" and much cooler than traditional applications.
I don't know what difference that would/wouldn't have on your application, but you will need to do much more accurate testing to prove whether it works or not.
EDIT: Read the sticky on how to improve your testing accuracy:
http://ecomodder.com/forum/showthrea...ery-11445.html