Headers on 2000 XJ

My 2000 XJ has pre-cats built onto the stock exhaust manifold...
Is it even legal to put a header on this vehicle?

Short answer...NO.

You live in Phoenix?? You are required to smog your vehicle?? A. It probably won't pass without the cats. B. Might even fail for visual if the smog guy notices the header and no cats. C. The o2 sensor readings may screw up the computer if you don't locate them properly pre and post cat.

Banks I think makes a header for those that keeps the precats.

That's the California / LEV emissions package. It has at least 4 O2 sensors, 2 upstream of the pre-cats and 2 just downstream. My '00 doesn't even have an O2 sensor anywhere near the main cat. You will throw CEL's if you mess with any of those 4 sensors. If you mess with the 2 upstream ones your engine won't run for crap since it won't be able to sense the air/fuel ratio.

Banks is the only header I know of that is compatible with the pre-cat setup. Magnaflow also makes a new precat / downpipe setup as well. But for those two pieces alone you're looking at a cool grand.

Borla 17601 for the pre-cat Jeeps.

AFE, JBA, Borla, Pacesetter, OBX and Banks all make headers for the 00-01s that retain the stock O2 sensor location as well as the pre cats. Contrary to popular belief the precats are not part of the stock exhaust manifold.

Talyn said:

AFE, JBA, Borla, Pacesetter, OBX and Banks all make headers for the 00-01s that retain the stock O2 sensor location as well as the pre cats. Contrary to popular belief the precats are not part of the stock exhaust manifold.

Click to expand...

Yep, they are part of the down pipe. So yes, it is perfectly legal to put a new exhaust manifold in place.