Older model header on '00 or '01

From what i've read the difference with the '00s and '01s is the number of O2 sensors on the manifold, right??

would it be possible to buy an older model header for my '01, weld on O2 bungs in the appropriate places and be good to go?? or is there something else that makes these years different??

ok, up until 1999, XJs had a conventional style/construction exhaust mainfold. in 2000, when they went to distributorless ignition, they also changed the exhaust mainfold. 2000 and 2001 models have 3 catalytic converters. 2 of them are integrated into the exhaust mainfolds while there is still one large catalytic converter rearward of the mainfold. pre 2000s have the flat style single catalytic converter while 2000 and later have the coffee can style cat.
2000 and 2001s don't have oxygen sensors near that rearward most cat. they have 4 and they're divided into 2 banks. each bank is a catalytic converter. bank 1 is the exhaust mainfold cat towards the front of the vehicle while bank 2 is sort of against the firewall. 2 oxygen sensors per "bank", upstream and downstream.
i have no idea what you'd be able to do in terms of oxygen sensor welding to make the computer not flip out at you.
if its messed up, go aftermarket, even though options are limited. the stock/OE exhaust mainfold is well over 400 just for the part, and that's online. a performance one, such as the one from gale banks engineering isn't that much more expensive, compairatively.
wow, i just wrote a lot.

Hmmm,my 2k has only 1 cat(by the muffler) and 2 O2 sensors.

my 2k has the 3 cats, last time i checked banks was the only one making a header. From what i recall the 2k uses a different style head, but then again the stealership told me this.

Some of the early 2000s had the 1999-style exhaust. I think that if you want to run a pre-2000 exhaust setup you're also going to have to completely switch over to pre-2000 PCM, sensors, and harness.

RCP Phx said:

Hmmm,my 2k has only 1 cat(by the muffler) and 2 O2 sensors.

Click to expand...

x2

There is a guy on JU that did the conversion with a Thorley header.

Curtis

i'm curious to see how he got that to work considering 2000 and 2001s don't have distributors. maybe he put a distributor in?
here's a picture of mine:

i've seen a 2000 that had flange bolted exhaust parts. mine, which is also a 2000, has exhaust connections between the pipes that are slip fit with exhaust clamps. i presume the systems with flanges are the older style.

He just did the header conversion, no change in ignition

Curtis