That's interesting Simon, because for my Roadster, Peter recommended a shorter reduced rate spring to retain the ride height, which replaced the original Plus 8 spec springs and damper blades..
When I did Bumble I just swapped the factory bearings for the Mulfab bearings. I didn't measure the difference........!
It's only a shorter spring, the rate is the same @ 140lb/in
Simon @ SiFab.co.uk