Hascol LPG station in Karachi won't fill gas with uncertified LPG Kits.
If you are looking to install LPG, your CNG Kit will easily fetch you 25-30K. Sell it and install Tesla LPG KIT from authorized seller. LPG cylinders are light weight, some are fashioned to fit spare wheel slot which is ideal for saving boot space.
Play it safe with fuel....