https://youtu.be/AGPbWDgFWUc
Found one more video about Flowmaster's exhaust for gen6 Camaro. No discussion/claim of "no-drone" with dual mode muffler, when valve closed.
I liked the sound of this system the best among aftermarket NPP system but I don't want to deal with drone on long distance drive. I've been asking about drone a few times (even on their youtube video) but no answer from them at all. I guess I should stop whining and forget about Flowmaster. Moving on......