Quote Originally Posted by ony View Post
for some reason I get better mileage with the egr employed.
it's not a coincidence. EGR does a couple of things that will benefit fuel economy including forcing you to hold the throttle open futher to maintain the same power output, reducing pumping/throtte losses.

if you completely remove EGR and add EGR spark to the main spark table, expect to run into knock often. the reason you can run more advance when EGR is active is due to EGR gasses slowing down the speed of combustion(so sparking earlier won't cause such detrimental increases in pressure too early in the compresson/power stroke cycles).