Extremely stiff rear suspension over bumps

[codemode]

Sorry if this is a stupid question…

Whenever I go over speed bumps the front end feels fine/manageable considering my setup is s-line springs and shocks all around with b5 perches in the front. The problem is the rear! If I go 12mph or a bit over the car just wants to leave the earth. It is so stiff you have to keep your mouth open so your teeth don’t break.

It’s a FWD, new (a few thousand miles on them atm) s-line rear shocks (cheap ones), tires are properly inflated (16”).
Could torn/worn bushings cause this or it’s the shocks. I’m wondering if getting the OEM Sachs ones would solve the issue. I don’t want to throw parts at it. Looking for a reasonable clue.

[TobiqueSlang]

It's probably the shocks, imo. I imagine the the S-lines are meant to carry more weight in the back end and on a FWD there's less so they don't compress like they should.

I'm also just making this up so I'm probably wrong but it's a guess anyway.

[Kevin C]

I swapped my OEM sport suspension shock for the red Koni special actives. Much smoother with good control.

[codemode]

I had a chance to drive a 230k miles one, but it was a quattro. It had an original s-line suspension from the factory. (aka never replaced) It was nowhere near as harsh.

My car is around 160k miles and none of the rear suspension components (except the sway bar links) had been replaced. That why I was thinking it could’ve been the cause.

Konis are not quite budget friendly (350$). Would a pair of used ones be better than a pair of new OEM ones?

Also I forgot to mention that I’m running quattro springs in the back because of the extra weight I carry at all times. Maybe I should’ve gone with the FWD version. But I was afraid the car would sit too low. Could a different weight category of the spring (one up) cause such behavior?

[walky_talky20]

Worth a look:
I have seen a rear sway bar cause this. It was seized up in the bushings pretty badly on the back of my Volvo V50 and made the ride extremely stiff. It basically acted like an additional torsion bar back there. I swapped in a new sway bar with new bushings and grease and it improved dramatically.

[codemode]

That’s interesting. They shouldn’t be seized since I replaced those bushings 2 years ago with Lemförder ones. I’ll defo check.