I picked this trick up in the Scirocco forums. It serves the same purpose as adding a bead of 3M Window Weld Urethane to the underside of the strut mount to keep the rubber from collapsing, a known problem with "all" aftermarket mounts.
Look here:
https://forums.vwvortex.com/showthread.php?7541657-34-years-ago-to-the-day-January-9-1982/page4
Basically a high quality exhaust hanger for Opels, available here:
https://www.ebay.com/itm/Goma-de-Es...e=STRK:MEBIDX:IT&_trksid=p2057872.m2749.l2649 Edit 07/28/2020, the link is dead, try this instead: https://www.ebay.com/itm/Goma-de-Es...527617?hash=item59272fb641:g:ZV0AAOSwQYZWxHTJ
Adavantages:
1) Dirt cheap, I bought enough for 5 cars from Europe for half the cost of one tube of Urethane.
2) No waste. The rest of the tube of urethane is wasted unless you have the energy to do all of your cars in one day (I do not)
3) No curing time, the parts are immediately and fully serviceable.
4) The gap stays super tight, better than Urethane.
I don't know if other hangers from the US would work, but the ones in the link fit perfectly (albeit hard to get in), and road impacts will seat them better and better over time.
Look here:
https://forums.vwvortex.com/showthread.php?7541657-34-years-ago-to-the-day-January-9-1982/page4
Basically a high quality exhaust hanger for Opels, available here:
https://www.ebay.com/itm/Goma-de-Es...e=STRK:MEBIDX:IT&_trksid=p2057872.m2749.l2649 Edit 07/28/2020, the link is dead, try this instead: https://www.ebay.com/itm/Goma-de-Es...527617?hash=item59272fb641:g:ZV0AAOSwQYZWxHTJ
Adavantages:
1) Dirt cheap, I bought enough for 5 cars from Europe for half the cost of one tube of Urethane.
2) No waste. The rest of the tube of urethane is wasted unless you have the energy to do all of your cars in one day (I do not)
3) No curing time, the parts are immediately and fully serviceable.
4) The gap stays super tight, better than Urethane.
I don't know if other hangers from the US would work, but the ones in the link fit perfectly (albeit hard to get in), and road impacts will seat them better and better over time.