The 'kamani' system is a decade old system of rear suspension support which was generally used in low quality cheap cars.
Nowadays, you may only find this system in some absolute pieces of bullshit like Mehran, Ravi and Bolan!! Better cars (or indeed those objects that you can call a 'car') have 'coil spring' system, including cuore. So I dont think you can install any kamani in cuore.
If their is a noise from the rear, then I suggest that you get your coil spring checked from a mechanic.
Generally, their are different coil springs for CNG fitted vehicle due to the extra load it has to take on. Besides in old cars (which are driven on rough roads, such as what we have in Pakistan), you can expect a high wear and tear and it wont be surprising if your existing coil spring has spent its useful life. It may still work without CNG but if you have a cylinder, have it changed.
Some people make a mistake by using an object called 'gatis', which is placed on top the coil spring and below the body of the car. This can only defer your problem by 5-6 months and you may still hear some noises.
Lastly, if you can afford it, then go for the genuine CNG coil spring for cuore. your problem will be solved.