My nephew just stopped by and he said the copy cats are called "Pro Sound"
He told me he took them off as he got tired of them. He took a walk in the junk yard and found 2 flowmasters and had them welded on. A friend of mine did this same thing, he found 2 laying in the junk yard, paid $30 for them both and walked away smiling. Since the guts in a flowmaster almost never rots they all sound close to the same when broken in.
I took the flowmaster off my 4.3 V6, as it sounded like a swarm of angry bees. I went back to what I know and love since my youth, a turbo muffler.
FM`s sure sound great on V8`s, not so good on V6`s.