I was going to install the Stew-Mac truss rod, but needed a 7/32" router bit. As I only had a 1/4" bit, I used my Luthier's Mercantile truss rod. I had to make two passes and that caused a slight enlargment of the slot. I will buy the 7/32" bit so the fit will be perfect next time. I messed up on the first pass when the bit grabbed some wood and went off course. Lesson learned: Route from left to right. Going right to left caused the bit to grab too much wood. Keep pressure on the guide piece and go slow. (The guide piece was away from me). No big deal, as I fixed the route with some walnut scrap. I am using a body adjustable design. As it will have one pickup, the wood removal is minimal. The mahogany body is so small as my uncle Abe gave me a piece of Honduran Mahogany over 20 years ago, and I thought I'd use it "one of these days." Well, it's "one of these days," and so, the narrow design.