for what it’s worth I have put Koni’s on two different coaches including the one I have now and I love them. They have made a tremendous difference in the ride on both coaches. I’ve never installed Bilstiens but it seems many think they are a bit harsh on expansion joints etc.
I don’t know that I’d spend the money on high quality shocks on the rear. I think the consensus might be that a Monroe on the drive axle would be plenty good.
Doug and Terri
2008 DIP 40 SFT ISL 400 Cummins
2017 GMC Sierra 1500