Yeah Max, the 3 or 4 XS11 cylinder heads I've seen, ALL had that mismatch or lip between rubber boot and inlet entrance. Distruption to smooth flow it causes. I 'cleaned up' that area with a dremel on another Eleven I had. Sort of a 'amateur' port job
I didn't notice a real difference in power on that one, but fuel economy on long cruises seemed pretty good.

Comment