im changing over from flat track to cross country ive been running an open air box wondering if that would be ok for cross country i know there is alot of mud and water. its a raptor 660 if that helps any i know i should get a 450 but i already have this one so its free

 

I would say you might want to put the lid back on the box......IMO for XC racing there is some risk of contamination with an open box. Of course it depends on the conditions too.........FWIW The 660 is a fine engine for XC racing........