I just got done installing front & rear Hellwig sway bars and BOY what a difference.
A little background; I am a "Car Guy". I have raced cars for 30 years, along with building and Fabrication, even to the extent of building several very high end drag cars (twin turbo, custom roll cages, chassis set up etc. etc.) for customers. Worked at a large Ford dealer for almost 20 years, started in the body shop, became Service Manager, then onto Operations Manager before leaving for my current profession. So, basically I have always done my own work and sometimes I may make things sound easier to do than maybe they are.
With that out of the way, I have a 2006 Winnebago Class C, 40,000 miles. I didn't really think it drove too bad at all, but I have also towed 5th wheel race trailers with a Ford Dually for years. However, I wanted to make the coach handle a little better so maybe my wife can feel comfortable to drive once in a while. Also, I like to tinker if you hadn't figured that yet. Ordered the Hellwig bars through Summit Racing Equipment, I paid $241 for the front bar (7008), and $243 for the rear (7180) shipped, I get "pro racer" pricing from Summit so expect a little higher price without discount. The front bar lower bracket needed a small modification to fit around the drivers side radius arm...a small notch cut out, no biggie. Ironically Summit's online catalog does not show the 7008 fitting the E450, only the E350, but Hellwigs catalog says it fits, so I assume this is why. The rear bar went on without any drama. The size difference in the bars is almost comical, new bars are very large in comparison.
In conclusion, the difference in highway handling is HUGE. They are very easy to install, and well worth the $500. I had also installed Koni FSD shocks last season so I'm sure that helps with mine too. I am now confident the wife can drive it with ease. Good Luck !