I have a chevrolet Spark petrol model. I want to get a CNG kit installed. Please suggest what is the maximum size of cng cylinder that can be installed and what is the actual capacity of CNG in kilograms that can be filled in it easily. I have heard that most pumps are able to fill only 8-8.5 kg in an empty cylinder.

I want a cng cylinder that allows at least 10 kg of cng to be filled at an average CNG pump. Please suggest if it is possible and also what should be litre capacity of such a cylinder.