Just finished fitting the new rear sprocket. The Diavel 43 tooth fitted straight on, but had to do a new chain. 3 links too short....bugger. I didn't want to go the cheap and nasty route of changing the front to a 14 tooth, and the 2 up on the rear gives me almost the same result.
It has altered the revs by about 300, makes getting away in 1st so much easier, but the added bonus I hadn't figured on is now 2nd and 3rd gears are much more user friendly. Tight corners I needed 1st for are now 2nd gear, and ditto 3rd gear for 2nd. Around town at 60 kph in 4th gear is now doable instead of the 3rd I used to have to run.
100 kmh is 3700ish revs in 6th, and it will actually now pull away (albeit not spectacularly) from there. 5th at 4100 rpm at 100 kph is a much better gear for that still.
Obviously not a mod you want to do if you are taking the bike on the track, but for me and the anal speed conscious country I live in, well worth it