as far as i know it won't be as loud... im not sure it has any purpose other than that..... it is a SOUND resonator, as in the sound bounces around in a metal chamber and amplifies itself, more or less. feel free to correct me if i'm wrong.
and the restonator should be very obvious. its the huge metal box that sticks off to the side on the piping, located more or less under the driver's seat. there isn't one on the stock exhaust, and there is on the borla... trust me you'll understand when you have it in hand
and again, I wouldn't recommend cutting it out. Not only are you cutting apart the bolt on system that you just paid quite a sum for, you are possibly reducing the gains made, since the exhaust was tuned WITH the resonator, and I'm pretty sure the car won't be as loud...