As promised - here is an installation that is 100% hidden within a stock body
Rear of the firing can - behind the donut retaining clip - cut off to let the new rear fitting fit within the body. The donut was also cut down to route the tubing. Only one side needs to be cut - it just depends on which side you want to route the tubing..
You can see on the bottom of the plastic body what needs to be removed for internal routing of the tubing. Only one side or the other needs to be cut out, I didn't know which side I wanted to route it before I installed it, so I cut out both sides (same as cutting off both sides of the donut).
Difference in length between the modified and unmodified tail insert.