over the friday i did some RESEARCH work for LPG, kits, stations and comparsion of economy.
base line 
The LPG tank capacity is larger then CNG tank with choices of tank SHAPE.
The chances of explosion are less then 90% unless otherwise some flame is in proximity.
At the current price of LPG & CNG the difference is less then Rs. 4 per / km.
The kit for Carb cars is 100% local assembled from imported parts, in Islamabad. Price is approx. 26000 with a 30 litre tank.
The kit for EFI cars - 2 choices Polaris & Landi Renzo price are in range of 48000 - 52000 with a 40 litre LPG tank.
In Karachi HASCOL at shahrae faisal is LPG station plus offering LPG Kits. Station is on city side of S.F when coming from airport at left after the Suzuki show room. The fitter guys act smart / proud (the typical attitude of low life niswar eating pan chewing gutka spitting who got access to computers and computer gadgets but no manners for public dealing) but can be calmed down if handled nicely