Not as far as I am aware, Straight run from the manifolds to the tips. I had this problem with my OEM one as well, but wasnt so noticable.
hmm lets just take a gamble and state that it could be the breather pipe for the intake pipe popping oil into the 1,2,3 cylinder and thus burning oil for the left exhaust pipe only?
(I'm guessing big time here...)
You could open the plenum and see if it's dirty with oil there... (ever cleaned it?) You could attach a oil catch can for the two breather hoses and see if it dissapears? Have you changed the plugs?