I have a Oct 2008 Maruti Zen Estillo car Vxi model

I have a Oct 2008 Maruti Zen Estillo car (Vxi model) brought from a Auto dealer in Kolkata. It is a petrol driven car and gives me a milage of 13.5 km/l in the city limits. I drive the car around 34 to 38 Km per day. I was considering to fit a LPG kit and converting my car from petrol driven to lpg version. Is it advaisable to do so? If yes, what would be the approximate cost? And where in Kolkata can I do this lpg fitment to my car? Any address - phone no -> please provide.