I don't suspect there would be any difference between a Limited and Laramie on any of those things? Guy in my office has a 19 Laramie and just put an ATAC on it.
Sounds absolutely sick. Too loud for my liking in the cab. Performance isn't dramatically different than mine, but sounds like it is. Doesn't have any mileage info yet, suspect it's gonna go down - his foot is always in it now.