I guess they break in earilier than they used too. Feeling the bike even at 300 I have now I can see that. I know synthetic will make them, or just about any other engine, run smoother. At 300 now it runs much better than it did new. It seems there is much more power in the low end and engine breaking has been reduced significantly. I'll see how it feels at 600 miles but from where I am now my trepidations against going right to synthetic are being reduced with every mile.
As far as the noise, what does it sound like? Mine seems to be quiet, at least within the range of every other bike I've ridden.........