2000-2001 XJ Exhaust

I have a 2001 XJ, is the exhaust manifold down pipe less restrictive that the 99 and earlier models? Is is worth installing a header on these years or just keeping the stock manifolds and going cat back?

If you have a three cat system it's not a case of just fitting an earlier model performance header. The two extra oxygen sensors need to be present or emulated.

I found a new header from Rugged Ridge for a TJ that may be an option but I don't know yet if there is any difference between the original equipment XJ and TJ 2001 headers.
http://www.naxja.org/forum/showthread.php?t=905521

tiburontropic said:

I have a 2001 XJ, is the exhaust manifold down pipe less restrictive that the 99 and earlier models? Is is worth installing a header on these years or just keeping the stock manifolds and going cat back?

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Later manifolds are better than the earlier mainfolds, less prone to cracking, and they have the 'pre-cats' with I think 4 O2 sensors?

I just went with a Rusty's Flowmaster 50 cat back and noticed a real improvement on my '01.

My 2000 XJ Sport has the kittens and the 4 O2S. Does that equate to Cailf. emissions?

My 2000 XJ Sport has the kittens and the 4 O2S. Does that equate to Cailf. emissions?

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Yes.

I've heard of some people with this setup go with aftermarket manifolds, but as Vince said, you would have to make provisions in your new manifold for the O2's. You can "Sim" the sensors, which places a dummy load at the connection which simulates normal operation. I believe this is also illegal, but it can be done.

-john