Cultus 2008 Suspension issue

[bilal.dynamix]

Hi ,
I am extremely frustrated with the suspension/shock noise in my Cultus. It is 2008, VXRi and driven 140000KMs. While driving on bumpy roads the suspension feels very stiff & suppressed. Also while passing over a deep pothole or hump a loud "Dugg" noise comes from the rear shocks-every time. This rare shock problem surfaced after I removed the CNG cylinder from my car. If the car is loaded- 2 or 3 persons sitting at back seat then there is no noise. I suspect that Suzuki designed the rear suspension/springs keeping in mind the weight of cylinder and removing it has caused the fault.
Please advise if this can be repaired or should I go for new shocks.

[bilal.dynamix]

6 days since I posted and no replies

Anyhow, I further figured out that the previous owner might have used a bigger wheel/Rim size than the specified ones. In order to offset that, he might have used bigger springs and may be spacers. And this is what is causing issues-
Any views on that?