I have some question about Wira 1.5 GLi SEDAN Auto....

Currently, when driving with one driver and one passenger (2 People in Car)...
This car has no problem crossing bumps.....

But, problem comes when there are one drive and 3 passenger (2 Front / 2 Rear)
The Car Bottom is kinda scratch by the bumps..... it's irritating and hope to solve it soon....

Heard from from that Proton Wira 1.5 GLi SEDAN Auto is normal with this issue....
When i come to my machenic, he said that maybe my absorber is not that "strong" already... so, that when have 2 passenger at backl... the car seemed to be lower....

Problem can be solve by changing the Shocks Absorber to....
1. Wira 1.5 Shock Absorber (REAR)
- problem solved a while, and will be back when shocks weak again....

2. Wira 1.6 Shock Absorber (REAR)
- Problem solved, coz the 1.6 Absorber is higher than Wira 1.5 one.... and 1.6 Absorber can handle more weight....
My QUEATIONS IS,
1. Can Wira 1.6 Shock Absorber fit and use it into a WIRA 1.5 SEDAN?
2. If i changed to 1.6 Shock Absorber, should i change the spring also?
3. What brand is good for overall comfort and performance?

Please Advice.
Thank you very much.

About 6 years old already...