I routed and attached to the same location as David’s photo, being careful about non-abrasive points. Would’ve liked it a tad longer, but it was just enough length. Give Allen a shout if you need it longer.
Thank you for posting your pics. Helped my understand how others are putting by oil filler tube. My oil filler tube is in the high pressure area of the upper cowl between cylinders, not behind it. (IO-540). So, I'm guessing lower cowl exit may be best place for my plug.
I like that clamping mechanism to secure the plug. Mine is just tied right onto the engine mount and the plug head flops around. I feel like I need to copy this.