Bilstein B4, M-sport, Harsh ride

[pegasusactual]

Thanks in advance for advice.
I installed Bilstein B4 shocks/struts and Suplex 06249/06231 springs on my 03 Z4 with factory sport suspension a few years ago (15K miles). It's an extremely harsh ride on the St. Louis city streets, so I'm pondering options for improvement. I'm curious of experiences with the B4 model absorbers and any conversions from M-sport to standard suspension along with any other advice to soften the ride.

I'm running Continental DWS06 18" tires. The entire suspension system for both axles was replaced in 2017, and the lower control arm bushings are fine. I'd like to concentrate the conversation on just the strut/shock and springs.

Options I'm considering
-Install standard springs and bumpers but keep the M-sport sway bars
-Install standard springs but keep the M-sport sway bars and bumpers (would this fatigue the springs???)
-Replace the springs and absorbers (model advice welcome)

This project is partly being driven as I need to replace the struts and shocks on a Z3. Many have recommended KYB, but there is a supply chain issue. The B4s are in stock, but I don't want to produce the same issue if that's the primary cause of the Z4 ride stiffness.

Doug

[Piper1]

I’m not sure I’d personally go with non sport from where you’re at due to the height difference and feel. You’d be raising where you’re currently at in height. A quick and easy way to help soften a bit is to go to 17” wheels and tire selection to help reduce road imperfections you’re feeling.

If it’s just dampers talk. My 03 has koni yellow adjustables eibach springs combo an fronts are 1 turn from max stiffness rears 1/2 turn from max and with camber plates MI roads it’s pretty harsh for daily and I can compare to my 07 coupe stock now on the same roads. Performance wise and ride height I just couldn’t see going to non sport so it’s kind of what do you want to get out of the car. A smooth daily cruiser or more of an aggressive cornerer.

[pegasusactual]

Thanks for the input. Trying standard suspension springs is the cheapest option, so that's the first try at softening the ride. I hope to have them installed over the long July 4th weekend.