Heck, get one of each and splice them! Put the 3.6 resonator and pipes on the car, then cut off and splice in the V mufflers. You'll have the best of both worlds . . . smaller diameter pipes to help scavenging and keep the exhaust velocities maximized, and the throatier stock looking V mufflers.
The alternative is Borla, Corsa, or B&B, but all run around $800-$1200.
You can easily make your own template from the existing hole on some paper. Flip it over and trace it onto tape on the other side of the bumper. Use a jigsaw to cut about 1/8" inside the line you drew and finish up with a dremel to clean it up. Then remove the tape and admire your clean new hole. I'd do this before I went to a muffler shop, since it has to be done before the mufflers can be installed. I think I'd be more careful doing it myself, since I'd have a vested interest in it looking good, than someone who's just trying to get your mufflers on.