I have had Flowmaster and Magnaflow...
I choose Magnaflow at all levels....
Flowmaster when you get on it sounds nice, but it drones otherwise. I never liked the fart sound it made at low RPMs.
The Magnaflow system I have now is WOW... I was sooooo impressed with it even with stock manifolds.
Inside the car it truthfully sounds like a Cobra. I crap u not.
Outside the car it sounds european V8 (if you can imagine it for a sec). When you get on the throttle it just sounds perfect.
It will never sound like a 5.0 or 5.7 and I never thought it would. I was going for the cool exotic sound of a Lotus or similar and I think I have found it.
My system is:
Stock manifolds (yuck - warranty reasons)
Custom downtubes (yuck, but flow better than stock 90 degree angle crap)
2 1/4 cats into 2 1/2 dual inlet Magnaflow stainless resonator
out 3" single to 2 - 2 1/2 pipes to each stainless magnaflow muffler.
All of which looks nice, but I kick myself every damn day for not specifying stainless piping...I dont know what I was thinking...
I cannot wait for headers, SCP downtubes and magnaflow cats!
I dont know what Dynomax sounds like, but many many people on here run the Magnaflow resonator and the Dynomax muffler setup and I have heard it on a 93 SC in the club here and I liked it.
He he he...My system rattles my windows in my house when it starts up (the car sits next to the windows by the way, the loudness is not obnoxious or anything)
Custom shop installed the whole thing for $1000 w/ cats & tubes so I was not unhappy.