Sunroof can be custom installed from many dealers and workshops but I would recommend you to go for Webasto, an international brand for supplying sunroofs to major car brands worldwide. You can get their address from their website and its workplace is located in Delhi. They open your car fully and remove the roof in order to cut it down precisely and add the sunroof. They use the best quality material and use anti corrosion paints and other stuff to keep your car safe from many points. You can confirm the cost of sunroof as it varies from model to model.