yup, outer and inner.
I used a boxcutter to just slice that outer ridge off. I used the same boxcutter to trim the last 1-2mm of the oxford heaterz as well (leaving the outer "ridge" on the grip itself intact of course).
I thought the grip would fit fine without removing the inner 'lip' on the throttle tube, but I was wrong, so I ground it down with the grinding wheel on my dremel. 2 minute job.
I left the ribs on the throttle tube alone, and didn't use any grip glue anywhere. Whatever, it worked. They took some force to get on. I can't imagine it would take LESS force to remove. Once they're in place I figure they "set" pretty good, just have some general stiction. Few hundred miles on em so far, no problems. I went the cables-down route, FWIW.