I think that's about what I needed to trim...the nose ring ply fits snug against the inside rear of the cowl spinner-face, and I had to radius sand the ply to permit the cowling to go flush. It was worth doing, as I think it ties everything together more rigidly. Not that a cowl is supposed to be "structural", but since I'm running a gasser, anything that makes it more solid up front is good for me.