Muffler Donut Hack
Um, ok here's a hack for those worthless VW muffler donuts: These last 10x longer than factory donuts. They can still get knocked loose though if the rock's big enough.
I came to this solution because I drive my VW's off road a lot with an exhaust extractor so the muffler was low under the rear right. It was always getting hit, so it leaked & cops kept stopping me for the noise. If the engine's reasonably cool, these can be replaced on the side of the road in 10 minutes without removing your muffler, (5 minutes if you're fast).
Spin a 12 inch length of fat yarn out of coarse steel wool, load it with Versachem Muffler Weld muffler patch. It's made from Sodium Silicate and clay, sold in plastic tubes or flat cans. Remove the muffler clamps that go around the exhaust pipes, force some of the paste in between where the heat exchanger exhaust pipe fits into the extractor tube, and wrap the string(yarn) around the exhaust pipe where the donut should go so it's a little larger than than necessary. Replace the clamps. Don't gun the engine for a while, or wait till morning. The stuff dries hard pretty fast, so wash it off your hands before that happens.
A backup reinforcement is this Muffler Brace. I don't sell this stuff, but you can give me money anyway.