Old guy - Lots of questions.

New to me 2005 C55 with Bilstein B4 struts.

Very much like the car
Would like ti a bit better if it was a bit less sharp in the response over the cracked/rutted up streets near me.

Would very much appreciate any advice/comments from those who have tried Koni or other struts.

Thanks.

Old guy - Lots of questions.

New to me 2005 C55 with Bilstein B4 struts.

Just to clarify, do you still have stock AMG shocks in the back with the Bilstein B4 struts up front, or are you using "struts" as a general term like "dampers"?

Very much like the car
Would like ti a bit better if it was a bit less sharp in the response over the cracked/rutted up streets near me.

If you haven't driven a C55 with stock AMG struts/shocks all around, you would have absolutely hated it if you dislike the ride quality of the B4's.

Would very much appreciate any advice/comments from those who have tried Koni or other struts.

I went from stock AMG struts/shocks with less than 50k miles on them to B4's because of the poor ride quality and control. It was a big improvement in both areas, but still a bit brittle for my liking. Typical Bilstein jitter, but much better than stock AMG. So, as an experiment I replaced just the rear shocks with Sachs Sport shocks a few days ago and I find it pretty much perfect now for my tastes as far as ride quality goes. It took the edge off the bumps/ruts but the car still has the sporty nature I expect from a sport sedan. I may switch the fronts to Sachs as well in the near future, but truth is I'm pretty happy with it now. In my experience with Bilsteins, even the B4 line, they always feel overdamped no matter what application I've used them and the rears contribute more to the overdamped feel and ride than the fronts. However, If your roads are really crap, you'll probably need bigger changes than just shocks/struts.

Do not know what shock is in the back.
Service record says "replaced strut assembly B4 OE" "strut mounts"
My assumption is - original in rear.

Would be worthwhile to take a look. If you have original, the B4's would be an improvement, and for all I know, perhaps more your taste than my preference in the Sachs rear shocks.

For the rear I would go right to B8....Ride quality is more a function of the uber hard factory springs than the soggy shocks in these cars.

I don't doubt the B8's would ride and handle better than stock rear shocks. Stock shocks are awful. They handle and ride poorly. It's like the AMG engineers switched their low and high frequency valving specs when they sent them over to Sachs to be built. However, B8's will ride more jittery and be harsher on bumps/ruts than B4's or Sachs Sport shocks. I also disagree that the rear springs are uber hard. I find them pretty soft and they allow for plenty of bodyroll. They are W210 E55 rear springs.

Maybe a Boge

Those are stock shocks.

After contacting Koni, I have reached the conclusion that no available Koni will give me an improvement in ride comfort over street cracks/ruts/seams etc. - all sport tuned to tighten up handling.
YMMV.