Do you really think the airbags limit travel on a HD pickup? I don't, the shocks and springs will limit before the bags will, and even then it's just not that much travel.
I had Firestone bags on a 2007 Toyota Tacoma and with stock rear springs/shocks the travel was not effected by the bags. I did a bit of 4wheeling in the truck and measured max travel before and after install, the shocks where the limiting factor.
If you feel like you need more travel and change the springs/shocks to allow for more travel then get the Carli long travel bags, otherwise don't worry about it.
