I went from flowmasters to Ultra Flows on my Barracuda. While they are not quiet they are WAY quieter than the flowmasters, the car also picked up .1 at the track as well. It makes about 550-600HP and for what it is the volume level is acceptable.
https://youtu.be/FEvTC9HFE0ILike others have said you might try throwing a glass pack in the system if you can fit one. My Jeep has a flowmaster 40 series and as I got older I gor tired of the 4.6L I6 making to much noise. I couldn't decide on a muffler change so I just had a muffler shop stick a 36" glass pack in front of the muffler. It kept the same sound but knocked the volume way way down. Now I can hear the rear end whine
