I blindly cut mine out.. Kinda. I figured I had to start somewhere. If it needed more, I'd cut more. I just like a nice rounded tunnel, no bigger than it needs to be with a smooth transition. There's a guy on fb that has shared the "split" tunnel and honestly, I just couldnt make myself do it and feel good about it. I'll share a Pic of his. It was alot easier (for me) to just start with a clean slate. Also pictured is a picture of my sheet metal rollers
View attachment 1716347042
View attachment 1716347043
View attachment 1716347044
View attachment 1716347045
View attachment 1716347046