Well I have always believe in that the -1 front = +3 rear
First thing to check before ordering your new sprockets.
Check the size of the chain. It may not be stock. Previous owner could have done a 520 coversion.
Second, how far back in the swingarm is your tire? If its way forward due to the larger rear... you may have problems going up in the front.
Then go ahead and do the front swap out... it will be cheaper than doing the rear swap.
aka Gas Man
Was: 2002 Kaw ZX-9R
is me till the