michael/edge, you are describing exactly what I encountered with my 07.5.
I was appalled at how much fuel I wasted to meet the EPA required smog stuff.
Its crazy that we have to spend a grand or two to delete 8 grand in emissions to get a good, clean running truck!
10 grand out the window so to speak but now for me I save on average 40% on fuel and to me that equates to a whole more non renewable resources not being burned.

Take this EPA