Not for those with a fresh new Flowmaster 40, until it breaks in a month, and you know how it sounds!
This is a theory of mine, but I believe it will work on single center outlet flows, I haven't tried it yet, because I haven't had time, nor the ambition, & energy to take my 6 month rusted Flow orig 40 off, But eventually I'll get to it,,, those of you who are ballsy, & willing, I'd like to know your results. Ok, here's the simple mod: All flowmaster orig 40's have an inverted V-shaped baffle plate as the final baffle on the exhaust, drill a 1/4" pilot hole directly in the middle of the inside of the baffle, then use the biggest hole saw you can fit to carefully drill thru the V-baffle (most probably a 2" hole saw) and you're done. This will free up the exhaust flow more like a straight thru muffler, but still leave some muffling, some of the exhaust flow will still go around the V- baffle, and some of the faster higher pitched pulses will go directly out thru the V- baffle first, & faster, this way instead of the exhaust flow roaring, & reverberating, and giving you a baffled hollow can sound, it should produce a louder, sharper, more defined sound, with less roar (but still leaving some baffling) and sounding like a good old steel pack. If you have a Cat on the vehicle, it's not very loud without a muffler anyway with a full tailpipe, I think this would be a most likely candidate for this experiment.
This is a theory of mine, but I believe it will work on single center outlet flows, I haven't tried it yet, because I haven't had time, nor the ambition, & energy to take my 6 month rusted Flow orig 40 off, But eventually I'll get to it,,, those of you who are ballsy, & willing, I'd like to know your results. Ok, here's the simple mod: All flowmaster orig 40's have an inverted V-shaped baffle plate as the final baffle on the exhaust, drill a 1/4" pilot hole directly in the middle of the inside of the baffle, then use the biggest hole saw you can fit to carefully drill thru the V-baffle (most probably a 2" hole saw) and you're done. This will free up the exhaust flow more like a straight thru muffler, but still leave some muffling, some of the exhaust flow will still go around the V- baffle, and some of the faster higher pitched pulses will go directly out thru the V- baffle first, & faster, this way instead of the exhaust flow roaring, & reverberating, and giving you a baffled hollow can sound, it should produce a louder, sharper, more defined sound, with less roar (but still leaving some baffling) and sounding like a good old steel pack. If you have a Cat on the vehicle, it's not very loud without a muffler anyway with a full tailpipe, I think this would be a most likely candidate for this experiment.
If not, a famous line from "Mission Impossible" the series: "Mr. Phelp's, If you fail, I'll disavow any knowledge of your actions, this message will self destruct in 5 seconds" 
