i would LOVE to see before and after dyno sheets following a tune-up! I enjoy fiddling with stuff and dyno-ing before and after. Did it with my maverick, FUN FUN FUN...http://www.youtube.com/user/TheScoop.../7/7DM5dvxl1ZQ
Mine is an 04, and I "assumed" they were cleaning the throttle body. Apparently not!
I cannot complain, though. My 04 Hemi is still pulling 20-21 mpg on the highway. Yes, this is as-per the on-board computer up above the windshield. I have heard that it is generous, so I ran a tank and calculated it by the pump numbers, and it was within .5 mph of the on board computer, so I am amped to have a full sized truck that pulls those kinds of numbers.
I drive 200 miles per day about 2 days a week, and over 100 miles per day the rest of the week, so good mpgs are important for me.