What are your actual goals, usage habits, and intent with your car?
If you want to add power either now or later, you need to consider a header. That's where the majority of the performance gains with this car come from until you're boosting it, or swapping a different motor in.
A catless header alone will gain a bunch of power and add a decent amount of volume, but the stock exhaust sounds pretty awful with it. If you can hear a catless header with a mild catback like the Invidia Q300, or GReddy Supreme SP you can get an idea of what a typical aftermarket setup on this car sounds like.
If you want it louder than that, get a louder catback. Invidia N1 and Tomei 80R are super loud examples, Perrin, MXP SP and Dezod are good examples of the catbacks that fill in the gap.
If you make a conservative choice with catback volume and you have a header and catback, and want it to be a bit louder, you can grab a front pipe. Getting a catless one will be much louder, but if it has a high flow cat, a resonator, (or two/both,) it will split the difference.
Edit: Nameless catback, 2.5" inlet with 5" mufflers is $650, and a JDL UEL Header is $750.
If you start there, you'll enjoy a bunch of extra volume, and still be able to add more with the front pipe if you see fit.
Intelligent part selection will help you gain power, lose weight, and tune the sound you want quite a bit.
Also keep in mind when you do a header you need to accommodate for tuning. You can have a local flash an OFT map on your ECU for likely $20 or a 6 pack.
