Hmm... despite the fact you're really
in the "frozen northlands" (so much so ya make me feel like I'm in the tropics lol) - you have that motor so snugged away I'd be a lil worried about overheating... ya might wanna open up the front to make sorta a "ram air" induction to assist cooling...
But, I suspect that from the gunk on yer snow pants that you may be suffering from no more than the very commonplace exhaust manifold leak, not only are those fasteners prone to loosening up (and are crazy easy to strip so be careful) if yer running the stock gasket ya may have noticed it's not very good... If you're indeed leaking there, I'd reco taking the muffler off & using a flat file to make sure the flange is perfectly flat (they're often curved/warped slightly frm the welding process) & picking up one of these far better gaskets: Sick Bike Parts
Jus' a thought