Borla doesn't seem to be real popular here it looks like. Most people seem to prefer the Corsa even though it's quite costly. With MDS the drone is what turns many away from brands.
Check this thread out -
Cat-Back:CORSA, B&B, BORLA, ZOOMERS, JBA, MAGNAFLOW. Some have sound clips available in the links in the first post.
There are MANY other threads with sound clips here of all makes. Do a search and I'm sure it'll help you make a decision.
Bernie