I have a 1971 Triumph TR6C with a very similar exhaust system to the '71 Firebird (except that it's in bright chrome)
It looks great and sounds even better.
Much better (IHMO) than the '71 low level pipes.
However I've picked up some really nasty burns from that stylish exhaust.
Proof that all that glitters isn't gold as they say.
I've always thought of the balence pipe assembly as an ugly rust trap, but it's got to be better than welding tabs onto a chromed pipe.
Has anyone been able to quantify any alleged performance gains over straight pipes ?