A few vendors have pipes that are bolt on. You can get one with or without a cat. Most places won't leave out a cat, so you may have to do the work yourself if you aren't replacing the cat with another. It may throw an engine code with no cat, but the sensor that detects that isn't necessarily needed for performance or gas mileage.

Vendors

Click on: ZZP, W-body, PFYC, Intense

ZZP has a greater selection I believe.

You can also go to a exhaust shop and have them weld in a new cat. You can get one for like $60-80 and then pay for labor.