My brother just got a YZ450 and compared to my DRZ400 the top end engine noise is rediculous. My DRZ400 had a slight tick in it that I was concerned about, but after riding several hours in the woods with my Bro. it's not an issue. How much noise is to much coming from the top end? I know that the DRZ400 has had some issues with the ACCT, what about the YZ450? Are there cam issues with the bike I need to keep an eye on? I've never been around a 450, so I don't really know what to expect. Should I check the ACCT and chain? Or should I take it to the shop?