So in that case, whats the pros of swapping to a 520 race chain then? I looking at the ERV3 actually... with a 520.
also note, around 9500 mileage... I take it front should be done too?
The chain you are looking at (520ERV3) is lighter and stronger than the stock (or most other) 525 pitch chains. At least you are looking at the right chain. No way I would want to put a weaker chain on a 999!!! The only benefit to the 520 chain is reduced weight/rotating mass. This is ideally for the racer who is trying to drop every ounce he can when on a race bike that it actually makes a difference. I find it hard to believe that you or I on a 70/30 % street/track bike, would ever know the difference in that 8 ounces of weight savings... But that's just me. For me, it's not that I don't think it's worth it, it just more so that I don't think it's worth the cost $$$. The cost of the initial upgrade, plus the cost of sooner chain replacements in the future. Got too many other CF goodies I'd rather invest in than spend that money on a 520 conversion.
As for the front sproket change now, that's mixed also. Some flat out say yes, some say depends on what the sproket looks like. My SS has 15,000 miles on it and the sprokets look great right now. No fish-hooking or anything. I'll make that decision to replace both when the chain 'needs' replacing next time.