No offense, but all of the exhausts you mentioned sound pretty reasonable for a high performance car with a high revving V6. As you've already acknowledged, it's kinda hard to engineer away the little sound foibles that are a matter of taste and still get full performance out of the setup, at a reasonable cost and complexity. None of them sound so horrible that the level of hiss and rasp should be a primary concern.
IMHO, live with it and be happy with the performance (or buy a toyota corolla with a massive stereo system and play a recording of a ferrari revving
).