Just purchased the G 4 months ago. Fit it with the textbook Eibach drop and a set of CV-1's. Now onto adding some pony's. Again, new to the G world fill me in. I am looking for a clean sounding car and stay within my warranty guidelines, until the chip and tune.G37S 6MT

 

If I'm not mistaken, nothing will add anything significant unless you mess with the electronics, which is definitely not within your warranty guidelines.
And new exhaust is I think what adds the most for our cars, but that's going to change the sound, so probably not an option for you.
You could replace the stock pullies with lightweight pullies. That won't really add hp, but it will reduce parasitic draw so it will let more of those ponies make it to your wheels. Has the added benefit of helping fuel economy, unless you enjoy those newfound ponies too much.
You could get tires with a smaller overall diameter. That would effectively reduce your final gear (which is all the wheels really are) and give you more power to the ground. It's not something I would do, but you could.

Oh! You could reduce the weight of the vehicle! Get rid of your spare, and back seat, ditch the G/F cuz she's weighing you down, remove your AC, get a park bench to put on the trunk, and stickers!!! Each sticker adds like 5 whp! Yea ok, I wouldn't do any of those either.

 

I thought I was the only Hoffmann that has the extra "n" lol