Sorry, Zahir Bhai, I did not read your earlier post properly.
I think some other brother, ALY, I think had asked the same question.
My opinion is that, since the Automaker, like Adam in this case, would know which AC system, CNG is best for their car and would have an expert technician to install it in the car, it is always better, to get it factory installed.
You can save the cost, by getting it fit from some mechanic later on, but that Mechanic, Mistry or CHOTA (little one or Apprentice Mechanic 
) has much less technical knowledge of the car, than the factory, specially in case of Revo. But, if you already know a highly trustworthy, and expert mechanic, and have an idea as to what you want, i.e. LendiRenzo CNG Kit, for CNG and also some well known brand for AC, it would be cost effective to have an expert mechanic, install the CNG kit and AC for you.
2 - I have read somewhere, I think it was Zakwild Bhai, whom bought a Revo 80 recently. When when went to have the AC installed in his car by a mechanic, the mechanic told him that, REVO has the Latest and advance set up for installing AC, which is a good thing.
I don't know about CNG, set up, but I think any car can have CNG set up in it without any special connections, holes in it. For the Cylinder, REVO has the best and most amount of space in the bootspace, even after the Cylinder is placed, REVO still will have more space left in the trunk than Mehran, without the Cylinder.
Just choose the best and trusted mechanic along with a good kit for CNG.
I hope I have answered the questions correctly this time.
