A lot of guys use Pacesetters. They come in coated (very nice looking and expensive) and painted (cheaper). Other companies include Stainless Works and Dynatech. They're more expensive but are generally very nice. You could cut the cats off and put in a "test pipe" if you know someone willing to weld it for you. Then you could get a tune for more performance and fuel mileage as well as cutting out the rear sensors. In an extreme $$ pinch you could patch in some test pipe yourself and install O2 simulators but I would not advise that....pretty cheesey.