One tip: I had a heck of a time with the drill bit side-slipping on me, so after fighting it for 10-15 minutes, I made this out of an old 10" long bolt hole alignment tool. You can get these at a hardware store for about $5.
Worked like a charm! A couple of light taps with a hammer to get it to bite into the curve, then a few good whacks to drive it through. Took all of 30 seconds per side. This makes drilling 10 times easier
Making the point offset to one side helps a ton with getting it to bite on an angle like in the pipe.
(My wonderful MSPaint work in the last pic is a bit deceptive as there aren't any "flat" spots accessible from the tailpipe. All you can see through the tailpipe is curve.
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