I have the MBRP race and agree with this guy. Here are some of my videos.I have the race version. I'll answer my questions to the best of my ability.
1. The exhaust is not excessively loud at low RPMs. It is completely tolerable and not attention-whorey at all. However, if you have a manual and rev match your downshifts to higher RPMs (like 3k+) you will get a lot of pops and some cackle. It sounds great and can draw attention if you want it, but it can also be avoided easily as well. I've never had complaints about my system and I live in town and leave at random hours throughout the middle of the night.
2. It can drone a little, but not bad. On the highway it is usually fine but there is one road I travel everyday and the speed limit is 40, I have to run in 5th gear and I find the exhaust drones a lot in 5th @ 40.
3. I just went on a 2 hour highway trip last night cruising 75+ the whole time and drone was not noticeable at all. The exhaust adds a little extra vibration to the car, but definitely livable and well worth it for the improved sound, imo.
I love my race version and I kinda wish it was a little louder, but loudness and what is acceptable is very subjective.