There were a few older reviews that stated the exhaust got louder over time (FSwerks), to the point of not being "stealth," anymore. But nothing recently AFAIK.
The problem with exhaust reviews is that there are a lot of variations in catted/catless downpipes, and free flowing intakes; which dramatically affect your exhaust and getting a specific RPM drone. It's highly subjective too. One person's exhaust, that is music to their ears; could be another person's nightmare. Any review you're after, you have to take into account their mods too, or it's not an apples to apples scenario, and you may not like what you end up with.
I have the MBRP catted downpipe, and that was an easy install with good fitment.
I originally bought the Milltek Semi-Resonated setup and loved it. No drone, a little bark when needed, but not stupid. Well this winter I thought I would take out the resonator and see what happens. Well, I love it even more. I drive 45 min one way to work every day and I can easily live with the sound. Highway it's reasonable with no drone and when I kick it down it sounds even better!! Like everyone else has said exhaust sound is subjective to the owner, but take this for what it's worth.
I have had milltek non res with a catless for over a year and a half. By far the best sounding setup I've heard and has no drone. It's also still loud enough to wake up the neighborhood when you put your foot down. I have no regrets purchasing this setup and wont even go EWG so I can continue to hear it's song.
I've been kicking around the idea of an exhaust to go with my catless dp and i was set on milltek non resonated until I heard a video of the thermal r&d that was kind of impressive. Just saying, not trying to threadjack.
I have the depot racing catted dp and Milltek non-res I don't think it's loud at all. Biggest thing is no drone! After that it's the best tone I have heard to me most 4 cylinders sound awful that's just how it is but Milltek worked some magic and my car actually sounds good now. Like everyone has said sound is subject to interpretation all that matters is what you think.