XI aftermarket catalytic converters??

Calling all XI'ers with aftermarket headers and/or catalytic converters! I'm dying to upgrade my headers and free up some horsepower but running cat-less is not an option due to emissions testing (and a more general respect for the environment).

Does anyone have aftermarket cats, and if so, can you give details as to brand, type, size dimensions, etc? I want to ensure that the cats I get will play nice with the XI's 'special' exhaust setup. I've heard one can use the section one midpipe/catalytic converters from European SULEV e46s but haven't seen if they'll work w/ the XIs (and I haven't been able to source them).

Otherwise, I'm pretty much at square one, only knowing that the pipe diameter is 2.5"... Any help is greatly appreciated, I'm eager to get the cat issue straightened out so I can move ahead w/ the upgrade.

I've got some stock manifolds for sale.

Otherwise just google some race cats and have them welded in.

I'm currently running a stock setup, no need to buy new oem headers. I've come across many different kinds of aftermarket racing cats, just curious to see what brands, etc. have worked well for others.

somebody's gotta have headers and aftermarket cats on their xi

I'm in a similar boat. My XI has 140k miles. Due to a poorly operating CCV and aged Vanos seals my cats died prematurely last year and I am getting the age old P0420 / P0430 codes. I've since fixed and tuned up everything on this car but still get the codes.

With the age of the car and the mileage, I can't justify dropping $500 or even $1000 for new cats when mine are working, just not up to the DME's standards.

I've ordered a few components off Radio Shack's web site with the intention of building an O2 Sim. Hope it works. (All web sales of O2 sims seems to have dried up, so I am forced to build my own)

Originally Posted by Mark M

I've ordered a few components off Radio Shack's web site with the intention of building an O2 Sim. Hope it works. (All web sales of O2 sims seems to have dried up, so I am forced to build my own)

Can also flash a tune onto the DME to remove the O2 sensor checking. This will also get rid of the check engine light.

FWIW race cats aren't worth it. Either keep the stockers, get funtional ones from the junk yard, or put in headers.

Originally Posted by SamDoe1

Can also flash a tune onto the DME to remove the O2 sensor checking. This will also get rid of the check engine light.

FWIW race cats aren't worth it. Either keep the stockers, get funtional ones from the junk yard, or put in headers.

1. Tunes that remove o2 checking also remove the readiness monitors. Thus not able to pass PA state insepction.

2. PA junkyards legally can't sell used cats. They have to by law scrap them for their precious metals.

Thanks to the bureacrats I am screwed again. Other than the damn cats my car is in tip top maintenance shape.

I'm with you two. I know threads have come up on the subject, but there has been little to no resolution.

I didn't realize DME reflashing removed the readiness monitors, I'll have to look into whether I would fail my VA inspection. I'm still really curious to know if I could cut out my existing OE cats and have them welded into section 1 of my exhaust...never got a definite answer on that either. At this point it all seems like too much work just for new headers.

Magnaflow offers a header/cat setup for $700-$800 (ea. front and rear) that lists as XI fitment. No poster ever talks about these. I'm guessing due to being more expensive then Ebay headers with Frankenstein pipe/muffler setups. The header need is questionable as some may not realize they take away from low-end torque and move the HP curve up to higher RPM to be effective for "gains".

Various brands below list as manifold/cats but the magnaflow appears as equal length, head pipes. Not sure if that would be a true "header"?

Check these babies out >> http://www.discountexhaustsystems.co...t,universal:0)

You will never pass emissions with race or high-flow cats so dont waste your time. The sensors are very sensitive and the monitors won't be ready to pass. LC-1 works
I have headers and they have improved the low-end torque a bit. I dont care about the torque cause im always at 6000rpm in first and second gear. The car goes, feels, and sounds much nicer.

Mark m
To really determine if your cats are no good. Try what I did
I removed my exhaust system underneath my BMW
because I was having a similar problem with those freakin cat codes.
After I removed the exhaust pipes I got a flash lite and looked up into the rear cat and to my surprise it was plugged but the honey comb shape was ripped in two places and the car ran great.
I could not see into the front cat because the pipe is to long and curved but good luck.
Normally only one cat always goes bad.
My recommendation is to buy the original
OEM CATS from the BMW DEALERSHIP.
Because if you buy them out of state your taking a big risk.
But it's your decision.
I know the cat are expensive from the dealership but you'll say time and money in the long run
I got a discount from the dealership he trimmed about 150.00 bucks
Anything helps.

Pa if you buy after market cat the CEL will still illuminate.

If you want to change the policy that BMW cats are so darn expensive
Call your local elected official and make a official complaint.
And maybe BMW won't monopolize the price.

Originally Posted by Adolf

If you want to change the policy that BMW cats are so darn expensive
Call your local elected official and make a official complaint.
And maybe BMW won't monopolize the price.

they are expensive because they are made with better materials. there's a reason $99 aftermarket cats are so cheap. they also tend to smell like egg farts and last maybe 6 months.

IMO, stick with stock.

Thanks but after 8 months of trying I finally gave up. I traded the car in.

I enjoyed driving the car, it was maintained like a champ and it was a rare XI with a 5 speed manual. I miss it, but economically I could not justify dropping $2000 for replacement cats in a car only worth $5000.

I got a 2005 X3 at practically wholesale pricing, have another post about it out there. In short, The X3 was stickered at $17,700, they wanted to move it to meet sales objectives, gave it to me for $13k - 5k trade in = $8k out of pocket.

What do you guys think about this setup + an LC1?
http://www.magnaflow.com/02catalytic...irectfit=24510

My reasoning is that i'll still keep most of the performance gains of the headers, pass readiness and still be environmentally friendly. Now I wonder if these will fit, since they are listed for XI but I'm not sure we have room where these cats are positioned due to our xfer case.

edit:
some research on real-oem indicates that no European XI ran cats under the body, they all have us-style cats in their manifolds. argh. I'll keep looking for a solution.

finally got these put on.



This is about the only place you can fit catalytic convertors on an IX with headers. I'll see if it sets readiness with the o2s being so far back. Worst case i pick up an LC1 to pass odb2 as this should pass me on the visual side of the inspection.

saw this outside as I was leaving, made me feel good about my "green" decision

extended my o2 sensors to reach my new cats:

picked up decent copper trailer wiring as it already has 4 wires together and would make life a little easier:

finished product

and then went out and drank a highland cold mountain ale (local seasonal craft brew)


Now i'll see if the CEL turns off by itself (fingers crossed) after several key cycles + hwy driving. If that doesn't do it, i'll reset it and drive some. If that still doesn't do it, time for lc1.

she just set cat efficiency readiness!

Just out of curiousity, what's the point of this other than to be green? Why didn't you just keep the stock cats? Are there benefits of having headers and cats vs the stock ones?