We put the Firestone Riderites on our Dodge this last summer (2013). Glad we did, we had a little "sag", maybe an inch or so nothing huge. They seem to take the bumps out of the road with the trailer on, I say "seems" because to us it feels better than without the added air.
The air bags help with headlight orientation at night, not that we do a lot of night traveling but the few times we did prior to adding the air bags we had people "flashing" us as they thought we were traveling with our high beams on and we were NOT.
For the money you can't go wrong. Just my two cents.
Dan