"Pre-Cat" or "Warm-Up Cat"?

[xjh3]

1997 XJ, 4.0, Auto, 231, 2.5" lift

I am looking into getting a PaceSetter header this summer when my financial situation allows me to replace my cracked stock one. I noticed that this header is offered from 1994-1999 and also from 1997-1999 but for Jeeps with a "Pre-Cat". What is this "Pre-Cat"? I know these kits come with a new downpipe. My downpipe has a bulge in the middle of it right under the oil pan and I was wondering if all XJs have this or if it is something that has to do with the Pre-Cat.

I would really like to elminate the stock downpipe with that stupid factory pinch, but I am concerned that I may have to order a header that doesn't come with a downpipe in order to keep this Pre-Cat installed.

Please enlighten this exhaust newb. Thanks in advance.

 

[j99xj]

Get the 1994-1999 one.
I have it and it fits great with a little custom work. (like welding but nothing outrageous)

I think Pacesetter is wrong on the years, Xjs didn't come with precats until 2000.

That buldge in the pipe is just where the pipe makes a transition from ~2 inches to ~2.5 inches. Either way it is best to have a smooth and constant 2.25 inches and the pacesetter header should come with a downpipe like that.

 

[tealcherokee]

i agree.... get the 94-99 one, and youll have to plug the egr. but theyre def wrong on the years, ie, theres no egr. and SOME earlier xj's had pre cats.... cali emissions... i think it started in 97 or 98

all had precats in 00-01

 

[BBeach]

So the latest precats from pacesetters will go all the way straight to the front of the cat? What diameter is theirs? If it's 2.5" then it sounds good to me. Theres no clearance issues with the ones with precats on a 98xj right?

 

[xjh3]

So, if I had a pre-cat, would it be in that location? Or would it be right after the header like I've seen on 2000-2001's?

Just want to be absolutely certain that that bulge is no type of cat because it looks like a bigger bulge than what I think size transition would be. Is there any other tell tail sign that would allow me to be absolutely certain?

 

[xjh3]

Or would it even matter if I eliminated my "pre-cat" with a downpipe without one?