So, studying echo-francis's fuel log and EWP install shows it was associated with improved fuel economy. But it is hard to tell how much of the improvement was due to the new pump because he did a bunch of mods at once. The EWP was installed Sept 2012. In March 2012 he had recorded 58.59 MPG (US) and in October he recorded just over 63 mpg. But there were a few mods in between, like wheel skirts for one. So maybe it was worth anything from 1-3mpg in highway driving conditions? BTW, the install was a bear. Here is the install post:
http://ecomodder.com/forum/showthrea...tml#post328930