I've got the 2004 Duramax 6.6 turbo diesel and I've talked to a few guys that said they were getting 22-24 mpg. One said something about Bullydog and can't remember the other. To make this easy, I don't believe it!! Best I ever got was 17-18 mpg, but usually average 16 mpg. I have the Hypertech programmer, great power gains for the money, but no where near 22-24 mpg. Am I missing something??