Not 100% sure what you are asking. You need sprockets specific to you bike to insure the bolt holes match to your carrier, and the offset is correct, for the front sprocked, you need to match the splines and offset as well. If you are asking can you go aftermarket, the answer is yes.
15-39 is nice for highway and long stretches of road, cuts down on the number of shifts in town too. 15-41 or 42 is very zippy and knocks quite a bit off of the top speed but makes 2nd and 3rd very useful - you won't use first gear much once you move away from a full stop.
I second Sprocket Center as a source, but since you are in Canada you might find it better to deal with your local stores (which should be able to stock this brand). Yamaha, Honda, etc, might have a crossover to fit your bike but it would be difficult to verify that. Your bike, a 900, has significant torque so a sprocket made for a weaker 300 or 600cc might not be strong enough for the purpose, better to go with something rated to fit your bike. That goes for the chain too.