WTH does age have to do with exhaust sound ?? I'm 41yo and I'd love to stick "Cut-Outs" on my car! J/K! ;>) ;>)
Anyways, when folks speak of Flowmasters, not many folks refer to the DELTA series. The DELTAs are OFTEN overlooked by MANY!
I have 40 Series Deltas on my 89 5.0 and I think they are TOO quite. This is given the fact that my 89 5.0 also has a 2.5" O/R H-pipe (read NO CATS). It is STILL too quite IMHO.
Before I had the Deltas installed, my car still had the OEM mufflers. It sounded all right, but was TOO quite for my taste. I wanted more of a HotRod sound, but didn't want the 2K drone from the original 40 Series Flows. That's why I went with the 50 Series DELTAs.
Some folks say that Flowmasters will get louder with age/mileage. I can't explain the reasoning behind this theory, but I think my Deltas are a "tad" bit louder than when they where first installed. Could be I added a K&N, 73 C&L, Hypertech Chip afterwards though. ??
If that dudes car has Deltas on it, I'd jump on that swap in a Heartbeat!
BTW, anyone have the link for that Mustang Exhaust Sound files website ??