For anyone wanting something that's not too loud, I highly recommend Hayward and Scott back boxes, really happy with mine, bought second hand from a forum member (thanks bradz!), mine is a daily driver, started up every morning before 7am, I live in a tiny village with the car reversed up against the house so I couldn't have anything too noisy. They're nice and quiet unless really pushing on and then still not particularly loud, almost as silent as oem on idle (apart from cold start for the first minute or 2) barely any drone, a bit bassy at around 2k rpm but that's it. Everyone told me they were really loud and not to buy them but I'm really happy, around £800 new I believe.
A little clip here:
https://youtu.be/sOBNnaFWdDk
A little clip here:
https://youtu.be/sOBNnaFWdDk