So i bought a 99yz400 a few weeks back and i have a few questions. First is that i nocticed that the exhaust has a prettty large dent from the rear tire hitting it. Also after i took it out the first time i noticed that there were tire marks on the exhuast. The first time out was mostly whoops and trail type riding. So i am wondering why my tire it hitting my exhuast and what can i do to fix it. btw im 6'2 and about 230. Also, the clymers manual says the bike needs 95 or higher octane. Is this neccesary? what do you guys run in your bikes as far as fuel goes?