It's common knowledge that Borla, like most others, makes, basically, glasspacks. That's an ancient muffler technology and is simple and cheap to manufacture. An acquiantance used to work for them and laughs that their $1000 Lambo mufflers cost about $49 to build. Magnaflow, BTW, uses steel wool with fiberglass around it, so just a slight variation. Heck, I thought everybody knew that. *shrug*
BTW, weep hole = good idea. With the mufflers all the way at the back of the car, water is more likely to build up, as they take much longer to heat up. Generally, you want the hole near the rear-most wall of the muffler, because the exhaust forces the water that way, anyway, and no more than 1/8" diameter. It's a good thing, too, to get the car out at least once a week for a one hour-plus drive to heat verything up. For those with long commutes, you should be fine.
I'd agree with you, but then we'd both be wrong. 2011 Mustang GT 5.0 6-speed