| Changed mine with the help of Rich at Louigi Moto last spring. Very easy on the SL as there's no outer lip on the drive sprocket/cog, so they slip straight off. He did the tension by hand and I've kept an eye on it all season. I've read several reports lately from race mechanics recommending that you run them very loose if you're revving the bike out, so I haven't been too stressed about an extra mm of play.
Since replacing I've done 6,500 miles, including 5 TDs, with no probs. Now going in for top-end service and I'll get them replaced then.
No idea if the 4v is more sensitive to belt tension, but I'm sure someone (Nelly) can give you the full details.
Cheers,
Ali | 
Threaded Mode