Its slower to accelerate and higher top speed. People would do that to get the revs down while cruising for better gas mileage.
Edit: missed the 14 front sprocket. That would be weird as hell to go -2 in front and -1 in rear. Standerd re-gear for acceleration is -1 in front and +2 in back. 14t front sprockets aren't recommended....

 

Well, first figure out what gearing is on your bike, whether if it is indeed 14/45 combo.

IMO, -2/-1 combo from OEM gearinig of 16/46 would give you faster acceleration and lower top speed.

-2 front sprocket would have engine rpm go up by 15%,
-1 rear sprocket would reduce engine rpm by 2%,
combined would increase engine rpm roughly by 13% for given rear wheel rotation; which is likely why your speedo is showing near 20% above actual speed.

To reduce engine rpm, you need increase front sprocket tooth and decrease rear sprocket tooth... that will give you higher top speed at lower engine rpm.

Acceleration rate is a tricky part, depending on the rpm range that you use mostly to accelerate.

From dead stop, you want to reduce front and/or increase rear sprocket tooth to increase acceleration.

From higher (freeway) speed, you may want more front and/or reduce rear tooth to reduce engine rpm while accelerating.