Better to change the rear, than the front. A smaller front sprocket places more stress on the chain. Changing the rear is a bit more expensive though, since rear sprockets cost more than fronts, and depending on how many teeth you go up, you may need to get a longer chain.
Changing the front generally requires a pneumatic impact or if you wedge the drive, a breaker bar with a large socket to break the nut. Changing the rear sprocket requires generally requires more normal tools, assuming you have the tools to remove the rear wheel. The rear in my experience is easier to change.
I just helped my friend change the front sprocket on his 848. Th swap was not that bad. you are going to need a 32mm socket and a breaker bar or in my case since I did not have one, we used a tree stake driver as a breaker. you will also need the 10mm allen wrench to undo the rear pinch bolts, a spanner wrench to loosen the eccentric, and a torque wrench "big one".
un bend the washer on the front of the 32mm nut, pull it off flaten it out on ground for re-use on install. with a friend holding the rear brake and in gear break loose the nut "left lossey righty tighty" undo the 10mm rear pinch bolts, slacken chain with eccentric spanner wrench, remove chain from rear sprocket, undo the 3 screws holding on the clutch master cylinder to clear front sprocket and chain, remove sprocket and chain
then do everything in reverse. make sure to torque the 32 mm nut, and the pinch bolts IIRC THE 32mm nut is torqued to 144ft lbs and the pinch bots are 22 ft lbs.
hope this helps i do not think i forgot anything, easier than it looks.
Its a easy swap, a impact gun also helps alot to take off the nut.Just remember to flatten down the washer really good before you loosen it.
I had the 14t on mine for a while and didnt like so much,lower speeds were alot better almost perfect but on the highway I kept wanting to shift
into 7th gear
,at 80 mph it was at around 5200 rpm and w/full termis it got old after awhile
I ended up doing a 15/39 wich cured my problem at 40 mph but the cost was 4 times as much,for as cheap as the front sprocket is its worth trying just remember to measure your rear ride height before hand because it will be different after you adjust the chain