Do it! I urge you - best mod I ever did to mine! Sadly after I had spent money on two different sets of cans, PC5, air filter etc etc etc - the sprocket was £15.
I don't recall exactly, as it's been al most 8 years since I killed mine (yikes!) - but I went 1 tooth down [or up - you will have to check] on the front - as that let me keep the original rear sprocket and chain; it also changed the stupid first gear from 110 indicated, down to 85 - though I also fitted a speedo healer after the sprocket, so I don't know what that 110 would have actually been (maybe in the range of 96-102?).
Anyway, it transforms the low speed use, so that you can happily use 3rd gear in 30 zones! Prior to that, mine was far too ON and OFF with throttle input.
I still have my digi gear indicator, speedo healer and PC5 (with plug in loom) in the loft - keep meaning to stick them on eBay, as they have been up there (and through house moves) since my bike was written off - that I have no idea if they still work; one would assume so. Trust me if you're interested, might be able to come to a deal where you can give them a try before you buy or something.