Come this October, Prime Minister Narendra Modi promises a Diwali bonanza for Indian consumers with major reforms in the Goods and Services Tax. Changes that would ostensibly make tax assessment and collection simpler and less burdensome. The plan, among other things, would involve reduced duties on a wide range of goods and services and pruning the number of tax slabs.The promise, made in his Independence Day address to the nation on Friday, has since cheered the consumer and boosted market sentiments — Sensex and Nifty put up a strong show in Monday’s trade.