I had flowmaster on my 2008 and it drove me nuts, and rotted out fast.
I'm thinking you must have had the Flowmaster 40 if you got allot of drone. You won't have it with the 50.
If the muffler rusted out in a short time, it's because the installer did not put it in right so the little drain hole could allow the condensation to drip out of the muffler. Or the hole got plugged with mud.