Sound is awfully subjective but I'd pass on the Flowmasters if you want a mellow sound. I've had several pairs of both brands and I'll never get another pair of the Flowmasters. I figure there is no need to sound like every GM muscle car.
I guess it is a good thing a Cleveland has a different exhaust note then, or my car might sound like every GM muscle car. (just being a smart ass, not taking offense)
Now the newer cars sound like crap to me. Something about the overhead cam, or something do with the way they send the exhaust gases out, they just don't sound right.
A lot of the sound is going to depend on how you exit the pipes. They will have more of a throaty sound if you use turn downs, and more "in your face" if you exit straight out. Of course the longer the pipes, the more it will quieten it down.
This is mine with 40 series mufflers.
http://www.youtube.com/watch?v=kBqerjNIT9k Mine have turn downs on them, but at the moment they are sitting just behind the header, so short pipes means loud exhaust. I am going to have them run back to under the rear seat with the turn downs and it will quieten it quite a bit. Mine is also pretty loud because of the build, yours would be a good bit quieter.
I think for the sound you are looking for, Bob's mufflers would do good. Run full length exhaust out the back, but use a turned down tip on it like the factory did instead of straight out. The more turns and length you have in the pipe, the more it will muffle the sound.
