I have an invidia gemini on my 350z and can't reccomend it enough. Lovely tone without being abnoxiously loud (even with HFCs) and brilliant quality.
Miltek is a good shout and probably around the same price point, their stuff is usually very well made although I've heard it's not much louder than OEM.
Ark and Stillen are great options too, but a bit more expensive as you say.
Japspeed is cheap and cheerful, you get what you pay for so it's never going to be amazing (probably won't fit properly and drone a lot).
Lastly I've heard a lot of mixed reviews about Cobra, some people seem to love them but I've also seen a lot of posts about issues with welds, rust, rattling, drone etc.
I imagine the "cotton reels" are probably mass dampers, aftermarket systems probably just have no need for them.