Great findings OP! My sedan still has original stock dampers and springs with an xi rear sway, m3 rtabs, z4m fcabs, and alignment tweaks to get the car as neutral as possible. It worked pretty well for the past year and I'm happy to report the ride quality has not noticeably changed but the car has much less understeer. I am planning to go the next step for a little more turn in and will probably put the stock m3 bar on up front with e36 bumpstops and see how that works because a shorter front bumpstop should promote less understeer since it is engaging later.

My ultimate goal with the sedan is as neutral as possible balance with a slight oversteer bias while maintaining the factory damper compliance because it really is very good. Even on very high speed canyon roads, the car can just blow through the bumps and not get thrown off the road.

Now I had some questions to clarify in regards to the damper options for Sachs as of present as it appears from your post that there is no way to purchase original ZHP sport dampers from Sachs anymore as the rears are now a softer unit. Anyone aware if the genuine bmw variant (33 52 2 282 461) is indeed the same as the newly revised Sachs (556-882) unit that none of us want or is it closer to the listed TRW JGT439T? If the genuine bmw unit has been updated as well to match the Sachs dampening, then forget it.

It appears now that the only option really is E36 M3 rear dampers (unless someone can confirm the findings of the 461 rears from bmw) but I'm curious with ZHP springs, has anyone actually compared the compared the compliance of the E36 M3 dampers on this car vs genuine original units that aren't blown? One of the things so many people love about stock ZHP suspension is how smooth it is on the compliance side. Something i'd prefer not to ruin or chase my tail on when the dampers go relatively soon I imagine.

Now for the fronts, has anyone compared the 317-541 and 317-542 recommended struts from the M sport E46 to the original Sachs ZHP sport dampers 317-539 and 317-540 and care to comment on ride compliance between the units? I'm just torn why BMW would use worse dampers on the post 9/01 sport package cars than they would for the post 9/01 sport and ZHP models.

Also can anyone confirm between the two front damper options that the dampers are indeed the same length?