What would be the approx. cost?
Practically, adding a disc into a motorcycle is possible and making it double disc is not an issue. The problem comes to the riding quality of the motorcycle as most of the bikes including Pulsar 150 are made with exact spaces between the various parts. Inserting a disc brake would effect the dimension in few mm, resulting in overall bad ride quality and malfunction risk. It is avoided as company describes that modifying any of the component and driving can lead to injury and the rider would take the sole responsibility for the same. Pulsar 150 comes with a single disc and company feels it to be enough for the required braking power. Even bikes as big as 700 cc have single disc at the front and single at the rear.