New Class C owner stability control??

Test driving a new show-room rig before buying will be a hit-or-miss when it comes to revealing handling issues. Once the rig is loaded with fresh water and all the rest, it will handle differently. But even then you won't know if the rig has handling issues until you get on the open road and then the environment around you changes for the worse. All is well until you experience a day full of gusting cross winds.

I advise to also upgrade your front stabilizer bar. Not just your rear bar. Having both front and rear stabilizer bars upgraded to "Heavy Duty" will help a lot. But understand that everything helps. There is no total cure. After-all, it is a huge box that winds will play with.