The tunnel came out very slick. I like the idea of bolting it on, so if you need to get back in there later on, it's not a big deal. Gives you some on top space to run wires and lines, later on if you want! I'm actually thinking of something similar over my brake booster, for access to adjust the brake linkage arms, since they are buried in the booster housing, making it imposible to get a wrench at them.