I am not such a believer. I had the Flowmaster Super 44 installed at 23,000 miles and the truck has 144,000). It still sounds great and I can still talk on the bluetooth (with the windows up or 1" down on the passenger side while sneaking a smoke from the wife (she knows though) Haha)

I feel that 2-5 Whp may be great, but I prob wouldnt feel it. The exhaust is holding up and cost me 300$. It was worth it to me at the time. I am seeing some very small weld spot leak holes. Whos fault this is I am not sure, but the installer guarentees the work for the life of ownership. I will let him check it out when i return home. Honestly the manufacturer (Dodge) doesnt even warranty it for longer than 36,000 miles, so I feel I got a deal. I have always been happy. To each his own.

Thanks for the education

 

If you put your truck on a dyno (I have) you'll find almost no gain with a FM muffler (and sometimes a slight loss).
Also, if you can get your head in there (or use a mirror), check the top of the muffler. Because exhaust is redirected inside the muffler, condensation tends to collect on the inside/top of the muffler. When I removed mine after 3 years, the bottom and sides looked to just have surface rust and a few tiny pin-holes. BUT THE TOP WAS SWISS CHEESE! and I'm not in a salt state...