Exactly! No one ever answers past “you should have one.” Not pointing fingers at anyone, I’m just saying. That’s something else I got, was the exhaust note. However, I don’t think my car sounds bad at all. It has the loud pop/rasp downrevving, but I think it sounds great.
I said f-it, though. I’m building straight pipes. They’re done, actually, but I ran out of paint and don’t have a vehicle to go get more right now 
5-7dB is a decent bit for a free-flowing muffler. The bullet/straight-thru mufflers don’t do much, and the big (read: I can’t fit them) mufflers quiet it down and make less power.
I’ll tell ya what. Going from essentially 2.5" open headers, to a 1’ long piece (a 90* off of the header) changed the tone a lot. I’m guessing just the extra volume is going to quiet it down a good bit compared to what it was. I’ll grab some video whenever I fire it.
I was going to do side pipes, but after looking at it again and again and again, it’s not worth it. I have to relocate my fuel filter, and everything is such a tight fit, that it’s not worth the hassle.
So, dumps with the OEM muffler hanging in the rear FTW.
EDIT: I’m aware of what the crossovers do, I’m looking to see if there’s proof of significant power loss/gain.