I'm not a professional driver so my skills at evaluating subtle changes in handling between vehicles are somewhat lacking. I have put almost 280,000 miles on two coaches (combined) and neither had any handling characteristics that were remarkable.

We have now driven some other coaches and all of a sudden I have sensed a change. The last XLII we drove did not track straight down the road. It did not pull, but if I did not concentrate and make constant minor adjustments it would have been all over the road. In other words I had to work at keeping it in my lane of traffic at highway speeds, unlike my coaches that just seem to track straight and require minimal correction.

That could be related to alignment or tire issues, but I now know why someone would consider adding something to their coach to minimize that characteristic.