From running a couple of catback exhausts with header setup, this is what I can say.
Granted this is NOT the Borla headers, but some headers I made for my single port 2.2L Impreza. The catback section for NA's you'd have to put in a resonator along with a MUFFLER at the end if you don't want the raspiness. This applies to straight-through mufflers especially. Baffle mufflers are quieter.
Headers made the sound, anything after that MUFFLES it to how LOUD you want it to be.
I have one of the LOUDEST NA exhaust at the time, DEEP non-raspy when HOT, and you can hear it 1/4mi blocks away. I DO miss it in a way. This is the vid: