Within reason, if you're talking about your IDI, an ATS should be allowed since it was a factory option for later years.
Several 7.3 PSD's used to pull in this area, and did fairly well for being mostly stock. In the last couple years, the trucks that are now pulling are far from stock in the same class. You'll still find a couple guys hooking with them for the fun of it, but it seems like the guy that has the most money in his truck is gonna wax it.
It sucks, it's just the local fair and everyone is out to enjoy themself, but 8 out of 10 trucks show up with over 500 hp easy.