K4 GSXR Rattly Engine

[Seademon]

Anyone here knowledgeable on Gixxers? My K4 600 has done just over 18k miles and the top end of the engines sounds really rattly like its got no oil.. Oils on the max but it just sounds rubbish - valves were checked and adjusted at 14k as per the manual - done a track day and its not made it any worse, just makes me a bit hesitant when I think about ringing it to the red line

Any ideas on what I could check? Going in for service next week so I'll ask them to check aswell.

Cheers