If it was completely up to me I would more than likely go with the ATR or Hooker system. But, I'm 17 and my dad thinks that I should at least keep it looking stock.
He's also concerned that unless I go with a muffler and pipes specially designed for the GN's, I will have trouble with the turbo and too much back pressure. I tried to explain to him that any high performance system will work, because they all have very little back pressure.
I told him that if I was going to keep the stock design, I would have my exhaust guy bend 2.5" or even 3" pipes for better flow.