Shocking discrepancy: B6 vs B8

[NewArt]

I am running this ad here below but I have a question:
«I have a set of B6 struts that are about 2 seasons old. When I went to H&R lowering springs, I found out that I should have B8 shocks due to the adjusted height. Is there any interest here for a good set of Boxster B6s ?»
These struts seem to be performing well at the track. If I go to B8s, what should I expect as a difference?
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[steved0x]

I thought height was the only difference, from Bilstein uk:

Bilstein B6 - A non adjustable sport damper which is painted yellow. The B6 damper is designed for the motorist that wants a sporty ride without lowering the car or changing the original springs. Bilstein B8 - just like the B6 shock absorber but shorter.

If the spring is not falling free at full droop I bet it is ok?

[NewArt]

No, it doesn’t have any slack but there’s not a lot of tension when unsprung.