Borla exhaust question

[05 Silverado]

I just put a Borla XR-1 round muffler on my truck trying to make it louder than what it was before. It already had a cat-back aftermarket exhaust on it from the previous owner. Not entirely sure what brand muffler it had but it sounded pretty good. I just wanted it to have that deeper, meaner tone. Well it is definitely deeper but quieter overall unless you’re getting on it. 

 

My question is would adding another, making it duel exhaust, make it louder?  It has just one with 3” in/out and a 3” pipe dumped before the rear axle. 

 

Besided adding headers, would adding another make it louder?  

[redsled2007]

Not louder, just in stereo.