Just a few words of advice from someone that has already gone through the expense of upgrading on sidepipes.
1. Drive the car some miles before you decide to make them pretty with JetHot coatings, etc.
I installed Stainless Specialties 3" ID mufflers. Great, great sound, but boy they sure get loud (especially at WOT) and you WILL need ear plugs full time if you want to be able to hear normal afterward. Hindsight being 20/20, I would have installed a Vortec cone ahead of the muffler (or some other device) to "knock the edge" off of them. Running race mufflers under a car is one thing...having them 18 inches from your ear is an entirely different matter.
Look at my pics if you want to see what the mufflers looked like before installation. Sure wish I had welding skills...I could save myself a ton of money.
-Dean #747