I've seen and heard numerous Hooker systems on GN's, and for the money, they are great. They sound very nice, and fit fine. They perform decently for street use, but I would always recommend having a dump cut-out to open up at the track.
If you're willing to spend more, then the ATR systems are worth it too, both in sound and performance. The single-shot 3" works fine, since our cars are not true duals, but, as mentioned, it's loud and does not have the most pleasant exhaust tone. I prefer to try and maximize both flow and sound, since you'll be the one stuck hearing it everywhere you go. ATR's SS dual 3" is gorgeous, but you may need to re-finance your home before purchasing and paying to install...
Although FlowMasters sound great, they are not an ideal muffler for a turbo application, based on how they're designed to work with an exhaust pulse, vs. a continual stream as in our forced induction applications.