When I did my Shiver swap 2 yrs ago I had the HyperPro progressive springs. I played with valving, preload and fork oil wt and I was never happy with the performance and was dumping the Shivers in favor of Ohlins cartridges. Then I swapped to single rate Race Tech springs and the difference was night and day. The bike feels planted but not harsh, no brake dive, it floats over washboard and soaks up the big hits. I'm extremely happy with the conversion.
Camel Tank auxiliary fuel tank for F series BMW twins. www.Camel-ADV.com