Can someone dumb up the exhaust process for me?

I have an 01 GT Convertible 54K. It has an intake, TB and Plenum, so much like the Stealth Stang, it needs an exhaust. Now, I am looking to replace the exhaust from the headers back. The problem is, I don't know enough about them to make an informed buy. What is the difference in Shorty vs. Long, full length headers? X-pipe/H-pipe/Mid-pipe/high-flow/Competition  Someone help!!
It will be my daily driver when I get home from Iraq in about 2 weeks. I want to start ordering parts so they will be there when I get home. Thanks for the input and education.  

You can't go wrong with a Magnaflow cat-back system:

http://performanceparts.com/part.php?partID=283162

It replaces everything from the catalytic converter back and will not only increase performance but make you car sound good too.  

http://www.magnaflow.com/02product/shopexd.asp?zone=all&id=3284

Good suggestion. Keep in mind emission laws if you have to get your vehicle tested. Diameter of pipe, muffler noise (drone issues), and fit are things to consider.

Borla and flowmasters-cannot go wrong with these either.
Good luck.

MC2  

Thanks for the input guys. I am also thinking that since it is a convertible, I will get some subframe connectors or something like that to stiffen up the chassis.  

Yeah, its already got some on it but weld ins would be a lot better.  

What I have on my 03 GT is BBK long-tube headers, the long-tube headers are best performance wise and are a lot more free flowing, but they do hang down fairly low under the car so bumps get scary, not to mention the install isn't too fun. Then the headers are going into a BBK x-pipe, those two pieces (BBK headers and x-pipe) work together because the headers are so long that the x-pipe needs to be a little shorter, so I would not recommend BBK headers with any other brand x-pipe, my x-pipe is a catted x-pipe so that I can kind of keep the tree lovers happy but still get some good power and torque gains. Factory mustang exhausts are usually h-pipes but x-pipes give a little better exhaust flow. After my x-pipe i cut off the factory mufflers and just welded in Magnaflow mufflers, these mufflers are a lot less restrictive on the inside but still fairly quiet. So instead of a catback system I just welded in mufflers onto the factory catback exhaust so I could keep the factory exhaust look (exhaust tips) but free up a lot of hp/torque. It sounds really good, and it was worth every penny, good luck with your exhaust. I also just welded in full length subframe connectors from Maximum Motorsports, the install fit perfect they did an excellent job on the product, and they feel great. Hope this isn't too late of a reply haha. good luck.  

I have a 03 GT that I installed with a MAC catback system.All I can tell ya is,my exhaust has a nice note outside the car at idle,was straight forward to install,sounds good inside the car when I get on it.But it's quiet enough you won't get tickets.Ho ya the price is right too.