Hello mate, glad you're enjoying the civic!
Don't think that there's that many off the shelf options (or at least there didn't used to be). Back box wise I've now had two custom ones - a power flow one, and then recently one made by a local company which in my opinion is a better job than the power flow one. Either way with a custom back box they can make it sound how you want.
I've got a supersprint centre pipe, but they aren't the cheapest, and if you were getting a back box made up, you might as well get them to do the whole lot.