AgsWin

So if I wanted to go with cats, what all do I need to buy in addition to the LT headers? Im new to all this stuff, but Im assuming the headers come from the engine on either side and then go into a Y tube. Do they make Y tubes that have the cat with it or does this need to be custom made? Is there just 1 cat or 2 cats on the NNBS's and would I replace them with 1 or 2? After the cats its just a single tube that will go into an ew muffler and then out the back right?

jaywoo

What you have right now is exhaust manifolds attached to your heads. From that, the cats are attached on both sides. There are O2 sensors before and after the cats. The after cat O2 sensors are just there to monitor the cats, make sure that they are doing their job. After the cats, there is a Y-Pipe, then a single pipe running to the rear of the truck.

As far as I know (which isn't very far probably) the only headers out for the new trucks are called shorty headers. I mean headers that are specifically designed for these trucks. Shorty headers, IMO, don't do squat, stay with the exhaust manifolds or go with long tubes.

With long tubes, you can do either a Y-Pipe with high flow cats, or what's known as an off road pipe (no cats). You can find either for the 99-06 trucks, but I couldn't say one way or the other that either will fit. You could also have an exhaust shop custom make you pretty much anything you want.

AgsWin

From what I have heard the Pacesetter LT headers will fit, but then you have to get a custom made Y tube.

My question is, that if I bought the Pacesetter LT's, and have a shop make me a Y tube, will I have the 2 OEM cats in place BEFORE the Y tube, or have the Y tub and then just 1 cat? Or 3rd option of getting a custom Y tube with the a cat instaleld in it?

jaywoo

Normally you would have the cats hooked to the long tubes, then the Y-pipe. The cat will bolt directly to the header collectors, if your collector is sized correctly, of course. A muffler shop can make a fitting if not.