I don't believe that any of the after market canisters increase the actual horsepower very much, if at all. I think the increased sound just gives the sensation of more power/speed. And if they actually increase the power any, it is a very expensive proposition. $500 for maybe one horsepower increase, MAYBE!
But the canisters do decrease the total weight of the bike, so there may be some benefit?
If you like the increased sound, go for it!