All kinds of threads about this, some with scientifical charts and rpm comparisons...likely find them near the bottom of the page in 'similar threads'.
Most go with a rear sprocket swap, just because it's easier to swap the rear than R&R'ing the whole side cover and gasket to do the front.
I put a 45 on the back of mine, was a great swap...only noticed the higher 1st gear in really slow rough stuff. Was nice to make it all the way through an intersection without shifting. Still had lots of top end...my '15 would top out at about 115km/h with the 45.
If you're not riding slow, rough, technical off-road, I'd absolutely throw a 45 on it. A 45 on the back of an otherwise stock set-up requires a 120-link chain. Someone said "There's no economy in buying a non-o-ring chain." (or something to that effect). I'm thrifty, but I agree 100%. I was adjusting the stock chain every couple rides. Put on an o-ringer with the 45 tooth-sprocket and never adjusted it once in a whole season of riding.