I’ve used Dynomax stainless steel welded UltraFlows for years without a problem. Absolutely love the way they sound on anything with a v8.
There are a lot of variables that determine how long any given muffler will last including but not limited to mounting location, driving style or even tune.
I’ll continue to use them as they have been my all time favorites for many years.
Here’s what they sound like in my car. 408 with full 3” duals out the back.
