This is my honest opinion on performance mufflers. This is from years of myself and freinds expeiriance. There can be some variance with diferent motors. Also a variance related to the internal performance build.
All round tube glass packs sound the same. Variance comes from length.
A simular to a glass-pack but louder is the SLP loud-mouth. They are loud on V8's. I dont like them.
All cheaper regular 3 pass tube turbos, sound the same. Exception is the dyno-max super turbo. Internaly it has glass-fill and flow direction plates. My choice in this area.
All heavy case welded SS or steel oval or round baffle style sound the same. Internaly the baffle flow directors are just welded in diferent configurations. Very little difference when there is any.
All heavy case welded SS or steel oval or large round. Glass filled straight thru sound the same. Variance will come with length or 2in/2out, 1in/2out or if it has split tube internaly such as, X internal tubing. Not alot of sound change though.
Three mufflers I have never heard or experianced in person are.(1) The hooker oval straight thru. It has a volocity chamber before exiting a glass packed core.(2) Dont know the name but it has a straight thru spiral core.(3) The dynomax-vt. Oval shaped with straight thru glass packed core. A flapper valve that opens as exhaust pressure/volocity increases.
In my honest opinion. The only difference you will get in sound, motor to same motor. Is the style you choose. Brand will be very little difference.
Sound and performance difference, will only come from various, different motors. Other variances involve the motors internal performance build. Also Headers, cats no cats, length and size of tubing, tail-pipes no tail-pipes, etc. One other is at various rpms.
Rounding up my opinion. Listen to any one of these styles. Hear what you like and buy what you can afford in that style.
I personaly only got real picky with more research. When I built a performance motor from the ground up. Sound sometimes wasnt as important as HP/TQ numbers.