I recently received a comment and message on YouTube regarding my exhaust, the individual swore up and down there was no way that is a 3.5... Guess I did something right because he is going out to buy the same setup.
It's slightly quieter with true duel, but I found that with the 40 Series I did not want to sacrifice performance. My opinion here... I just don't think the 3.5 creates enough back pressure to warrant two mufflers (at least with a flowmaster setup, other brands might prove different), again just my opinion.