Changes in sprocket size can do many wonderful things and fine tune how the bike puts the power to the ground.
Changing the rear sprocket more directly affects top speed in each gear.
Changing the front sprocket is more dramatic and actually changes the characteristics of how the bike makes power, due to inertia.
You can get nearly the same final drive ratio by changing the front OR rear sprocket, but how you want it to "change" determines which sprocket to alter.
Example.
15X50 is 3.33
and
16X53 is 3.31
They are very similar ratios, but have dramatically different effects on the bike.
The 15 tooth front sprocket will be easier to turn because it has fewer teeth (distance) per revolution.
The 16 tooth must pull the extra distance in the same revolution. (Mathematically requiring more power to do the "work.")
Even though these "distances" are nearly equaled by the rear sprocket size, the inertial effects are greater at the engine sprocket.
I would expect a 15x50 to "rev" faster than the 16x53 setup.
Alternatively, this 16X53 can be used to smooth the hit of the engine, just like a flywheel weight. But the weight is at the counter shaft.
Trial and error for every bike is different.
-BIG DAN