Go to the vendor section of the forum:
http://www.giuliaforums.com/forum/802-vendor-deals/
and you'll find the options that are available that actually work.
As far as lowering, the Giulia was designed by Ferrari and Maserati engineers and developed at the Ferrari development facility, including wind tunnel testing. It has the best chassis setup of any car I've ever owned or driven in the last 48 years. Mod carefully, and do it stage by stage if you do anything at all. The car 'learns' anything you do, and starts making adjustments that you don't even know about. Lowering it is going to change its airflow, as well as make it more likely to scrape something on a driveway access.
If you're really suffering from a bad case of wheel-gap-itis, you can get spacers (I know Eurocompulsion sells a set including the longer lug bolts you'll need) that will move the wheels outward. That will lessen the wheel gap as well as slightly improve the handling.
The vendor section of the forum has several options for exhaust. Each one sounds different, so be sure and listen to the sound clips to see if you can find one you like. Be aware that resonance drone at around 2,000 rpms is a known issue for many aftermarket exhausts, so if you spend time driving (as in your typical freeway commute) at around those rpms, you probably won't like the drone. You might try an axle-back exhaust first, to see if that does the trick for you. If not, you can then add the catback component, including the possibility of a straight-pipe. It'll definitely be louder. Keep your stock system in case you decide to switch back some or all of it later. As for performance, if you've done nothing else to the engine/intake, just an exhaust can add 5-10 hp.
Honestly, if you are looking for performance, adding Eurocompulsion's V2 intake and their Phase 1 tune will do far more for you than any exhaust at any price; and some of them can get pricey. Whereas an exhaust will add 5-10 hp, for about the same money Euro's intake and tune will add about 60 hp, and that's no exaggeration. I have them with the stock exhaust and they literally transform the car to a whole new level of fun. That combo isn't temperamental either, it actually improves the daily drivability of the car. Mine is my daily driver and I couldn't be happier with the Euro people and their products.