Dear AquaTune, Having been satisfied with your product and the 25% increase, for quite a while, I started studying the instruction sheet over again and by simply straightening out the placement of the processor so that the injection would go smooth and straight in and slightly shortening the line, is when my fuel economy really started going up on my '04 Ford Freestar with the 4.2L V-6 OHV engine, I started out getting 14.7-15.1mpg in town driving and 19.3-20.2mpg on the highway. Now, however, I'm getting 20 to 20.7 mpg in town and on the highway 25 to 27.7 mpg at 65-75mph. Remember, too, that I drive with 4 Hankook HPW401 snow tires @ 42PSI, the year around! That is a 35-40% increase in my fuel economy. All this going up a 550 ft. climb in altitude & the hp is quite impressive, as well. Am I happy? Yes, otherwise I wouldn't be writing this.