Hi, re the aftermarket back box, I fitted one about two years ago and it appears fine. Mine is my03 so really not worth the investment for new.
I purchased the new one from eBay, shipped from.poland and came within 3 days. It was complete with suspension hangers. It included the central box too.
My Indi had it fitted within an hour, so not a huge job.
Looks fine and no difference in noise to my ears.
https://rover.ebay.com/rover/0/0/0?m...2F401141110438
Hope this helps