• Welcome to the new NAXJA Forum! If your password does not work, please use "Forgot your password?" link on the log-in page. Please feel free to reach out to [email protected] if we can provide any assistance.

2001 xj high-flow cat recomendations?


NAXJA Forum User
I have a 2001 Jeep Cherokee XJ and I was wondering which Flowmaster high-flow catalytic converter to order (part number)?

Other than the headers, I am in the process of redoing my entire exhaust system and trying to figure out what parts to order.

Although it's an 01' CA emissions Jeep (has pre-cats) I live in Massachusetts and since it's 20+ years old it does not have to pass an emissions test per MA law. So passing emissions is not something I have to worry about.

So, What's the best high-flow cat route to go for the best exhaust in terms of power and sound without losing back pressure? (and without breaking the bank)..I do not intend to straight-pipe it..

I've decided to go with an entire Flowmaster setup with 2.5' piping from front to back with Performance-curve.com and have it all welded together.

Here is my plan:

Flowmaster Super 40 muffler with the mandrel bent pipe from performance-curve.com

2.5 Adapter

I also need to order and cut about 9 additional inches to make up for the space between the muffler and the cat.

Now just trying to find the right Flowmaster high-flow cat to order.

other than that is there anything else I am missing?
Don't forget you have 4 O2 sensors and they're all around the precats on the bottom of your manifold.

There is NO O2 sensor at the rearmost cat on an 01. So changing that cat out and geting rid of the others will net you a CEL.

I went with the magnaflow precat setup on mine. Its well built.
I don't understand your overall plan. Are you going to eliminate the pre-cats and do a manifold-back exhaust?

If you are asking about the rear cat, I don't think you have much choice if budget is an issue. There are a number of universal cats with 2.5" in/out for less than $150. With all the cat theft happening these days, probably best to go with a less expensive cat. I'd go with Magnaflow.