Electric exhaust cut outs

I had 2014 Porsche Cayenne GTS with the 4.8L /420hp power plant a few years ago, it had dual exhaust with factory exhaust cut outs, they would react in seconds on WOT and close up fast, lol I opened them regularly and they never leaked or caused any issues over the 40,000 miles of ownership, wonder what they did different to have them not leak?