So I bit the bullet today and butchered my B17. I templated the cutout shape from the C17 Carved (which is a different cutout shape from the B17 Imperial). Just finished a 25 mile ride with it and not a hint of numbness. I haven't punched holes in the sides to lace it like an Imperial, and around the cutout I just gave it a coat of poofhide - I don't know how to give it a nice finished edge (burnish?). But my riding experience was very positive. And my B17 is blue, which is a color you can't get with the Imperial, so this is now a real one of a kind. Happy camper.