Read before you decide
I had a Bombz Evo N1 installed and was more ricey than I wanted but fit perfectly in the cutout and looks damn good. I went back the next week to have custom piping done and the resonator removed and now it sounds much deeper and don't have to cring everytime I open up. That one week before I got the customer piping done I used to try to hide myself in the seat but now it's not bad at all and can keep my head up.
As far as Borla goes, I have a friend with a 318ti show car and that exhaust sounds like it's coming from an 8 cyl muscle car. I checked their site and found them to expensive for my budget though. not to mention I couldn't find one for our cars.
Definitely read and get opinions before you go doing what I did.