I decided to try this combo since everybody has been using Joe-Z.
K&N was $265 shipped and I forget what the catback was $1300 or so.
Installed the K&N intake... Sounds MUCH better... Sounds like a V8 should. You can start hearing the difference at roughly 2k rpm and full throttle it really does sound like a race car. The car no longer sounds like chewbacca when accelerating. Did not really feel the difference however that might of been because I was distracted with the sound which was LOUD.
Got the Borla cat back installed today. It sounds beastly. I love it. There is drone, but that's expected on an aftermarket exhaust. The car turns heads when I go over 2k rpm, every time.
At full throttle there is absolutely no comparison from stock to aftermarket. It is LOUD. It idles slightly louder.
It was definitely worth it for the sound alone, it sounds good and can get really loud. HOWEVER, Borla is known for making poorly fitted exhausts, and I was the recipient of one... The installer basically told me Borla f'd it up and if I hear rattling to come back and he's going to try to work with it. He said the exhaust might start rattling when it warms up, and it did. He said some guy had one put on his Mustang a week ago and same thing happened.
...So I'll have to go back which I really hate doing. I'll get sound clip up / vid tomorrow.