How are they compared to B4? Sportier/stiffer? Are they comparable to B6/B8?
Much better but not stiffer, at least in suggested 3/4 front, 1 1/2 from soft rear settings. B4 is a less progressive damping I think, certainly with the M-Sport slightly shorter spring. It’s almost like the damper is slightly compressed and thus only has a stiff damping effect. Haven’t had B6/8 to compare.
The “buzz” from slight bumps and divots in the road has gone almost entirely, large bumps are still nicely damped. You can feel the road underneath you, but aren’t thrown around or impacted as much. Pretty sure my top mounts have degraded quicker in 10k miles because there were harsher impacts through into the body.
B4/MSport were good with big impacts but pretty poor with the smaller stuff.
Since changing them even on a 5 mile shakedown there’s been a few bits of road both myself and
@CaroleHeidi drove over and winced pre-emptively because it was crashy before and .. it just rode over it nicely. (We’ve probably done 4k on B4/MSport driving in a spirited manner between us.)
I had B4/SE Springs on the 2.5i (and 16” wheels) and that rode nicely. Occasionally crashy, but it is a sports car after all. I read up on it before fitting the 3.0si (18” wheels) with the slightly shorter springs and thought it would be fine. I’d now strongly recommend not doing B4/sport springs, koni’s are much better. Or B6/8, whichever is less stiff and handles shorter springs (B8 I think) as UK roads are pretty terrible.
Upside is the money I’ve spent on the Koni’s means I no longer need to spend money on 17” wheels to make it ride nicer
(I’ve forgotten who you are to tag you, but was speaking to someone on the Nationals who said a 3.0si on Koni’s was the best ride you’d had in a Z4 - I completely agree and am so thankful you mentioned it.)