Drat. Thanks for following-up though. I truly hope the cat does the trick for you!

 

Tony, I thought you had a SuperSprint header.

 

IMHO the MCS just runs so pig rich (esp at WOT) that any cat has to be really high quality to last in that thermal reactor hell. The stock part is definitely a quality piece (as it was designed for the mandatory EPA 8 year/80,000 emissions warranty on Specified Major Emission Control Components) so I wouldn't expect any problems using it with any header, and is exactly why I've recommended Helix's OBX/stock cat combo if you must have a header.

 

Good memory Norm. Yes, ceramic coated SS header, w/ stock cat... I've been getting codes almost since inception, and debilating ones at that: P2300, 2303 and PO172.

The good news is that I've been engaging some serious NAM brain-power (namely Dr Obnxs & 002) behind the scences. As of late last night, I'm leaning toward the cause being twisted O2 sensor wires making for the faulty & sporadic issue...

 

I was real careful with my 02 sensors and wires by unplugging them before removal from stock header and CAT when disassembling, The rig I put together has not tripped any lights or codes, it has been tested.
I’m running a MagnaFlow 91036 CAT, 2.5" in/out. You could run the same rig if you’re welding on of the stock CAT hasn't messed up the SS flange.
Check it out =
https://www.northamericanmotoring.co...&highlight=obx

 

That might be the same CAT my mechanic offered to use on the Milltek header. I do remember magnaflow being the brand.

 

Thanks Norm. You did a better job than me! I usually do things to the nth degree... but rushed the header install as the ceramic coating took longer than anticipated. What a big mistake that was!

Just confirmed about an hour ago... that my O2 sensor wires were twisted and too tight. That explained the issues I was noticing when taking hard turns. Life is dandy once again!

 

So your problem is solved?

 

I'm having P0420 thrown every other time I drive my car.
Can hear rattling coming from my one year old Milltek header.
Pretty sure its the cat.

 

Thanks Mickey for closure on that question. Given the sound, I bet you are right. A distinctive odor apparently should also be present...

 

Most probably P2270 (Catalytic Converter below Threshold)

 

Hey, I appreciate the follow-up.

Just noticed that 002 asked me a question earlier! FWIW, I got back with him via email... YES - problem resolved (tight & twisted O2 wires). She is running well, and I'm so happy.

 

So here’s a tip for those who have not discovered this already, when re-installing the 02 sensor, wind it up counter clockwise as far as you can before hand so when screwed in the wires will be relatively relaxed, also use anti-seize starting at the third thread.

 

Keith, I actually did that... turned it the opposite way before engaing the threads. It's just better, I feel, to disco the O2 sensor wires at the connectors so this won't happen... and still do the counter clockwise spin...

That's what I get for rushing!

 

Here's what I did. I made it so that my mini-mania header had a flange welded so that if my cat goes, I do not have to take my header off. This is also frees me up to try other cats or no cat.

 

Nice job, rig with added flexibility.

 

Where did you get the flanges / gaskets ???

Thanks

 

I got the stainless steel flanges and gaskets from a place called verocious motorsports. The metal cat and o2 bunge was from performance curve. I also purchased an o2 adapter from Mini mania. Call Eric at mania.