Messing around on this forum, and others, I've seen a lot of people do the XCal3 flash tune for boosting performance and fuel economy. The Economizer seems just for fuel economy. How many mpg's do you gain with the Xcal3?? The Economizer is claiming 10% and I've seen people with the XCal3 gain 15% or so. And which is better for the money?? any advice at all would be great!