Werks Downpipe

EnderWiggin

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2012 Regal GS
Thread starter #1
I'm out of town for the next month and a half, but I have one of the high flow cat downpipes waiting for me once I get home. Questions for you guys who have one, did yours come with bolts to attach to the midpipe, if not which did you go with? Also, will stock O2 sensor for the rear work, or do I need an extender to avoid a CEL? Thanks in advance.
 

Walt G

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#3
When I bought my downpipe from Werks, I'm pretty sure he gave me bolts, nuts and lockwashers, but I think I liked the factory hardware better and reused it instead... if I remember correctly.

As for the 'high flow cat' and a CEL... my opinion is that the 'high flow cat' is only good for 'maybe' passing some visual inspections in some states... you won't fool the car's OBD system, and you will get a CEL for catalyst efficiency.

And the OEMs have been pressured by CARB to detect extenders for years. Well, technically they are being pressured to detect 'slow response' sensors, which is what an extender does. They are getting pretty good at it. I'm not sure anyone here has had total success avoiding a cat monitor CEL with an extender without setting a 'slow sensor response' fault instead. I could be wrong, but it's a very fine line between passing cat monitor and failing slow oxygen sensor response.

If you find one (an extender) that works, let us all know how you did it. Other options include tuning out the monitor, or ignore the CEL and swap in the stock part when emissions test time comes.
 

GS’sGS

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2012 Regal GS
#4
When I bought my downpipe from Werks, I'm pretty sure he gave me bolts, nuts and lockwashers, but I think I liked the factory hardware better and reused it instead... if I remember correctly.

As for the 'high flow cat' and a CEL... my opinion is that the 'high flow cat' is only good for 'maybe' passing some visual inspections in some states... you won't fool the car's OBD system, and you will get a CEL for catalyst efficiency.

And the OEMs have been pressured by CARB to detect extenders for years. Well, technically they are being pressured to detect 'slow response' sensors, which is what an extender does. They are getting pretty good at it. I'm not sure anyone here has had total success avoiding a cat monitor CEL with an extender without setting a 'slow sensor response' fault instead. I could be wrong, but it's a very fine line between passing cat monitor and failing slow oxygen sensor response.

If you find one (an extender) that works, let us all know how you did it. Other options include tuning out the monitor, or ignore the CEL and swap in the stock part when emissions test time comes.
I purchased a ‘12 GS last fall and am also interested in installing the WERKs shorty down pipe with high flow cat along with factory GM Stage cai kit.
From reading your your posts it will always throw a code and get a light. Will a pro tune eliminate this? Any other options?

Thanks,GS’GS
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Walt G

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'12 Regal GS
#5
I believe that a good tuner can make it all work (BNR for example)... skip the GM Stage kit if you want to change the downpipe is my advice. The stock intake already is free flowing and pulls in cold air from in front of the radiator. The GM stage kit makes its power from the tune that comes with it, not the intake. A good tune with a high flow downpipe will beat the GM stage kit. Go Stage kit if you want to stay with all GM-approved parts, but I think you'll need to keep the stock exhaust that route.

All my opinions... do your research.
 

EnderWiggin

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Thread starter #6
I believe that a good tuner can make it all work (BNR for example)... skip the GM Stage kit if you want to change the downpipe is my advice. The stock intake already is free flowing and pulls in cold air from in front of the radiator. The GM stage kit makes its power from the tune that comes with it, not the intake. A good tune with a high flow downpipe will beat the GM stage kit. Go Stage kit if you want to stay with all GM-approved parts, but I think you'll need to keep the stock exhaust that route.

All my opinions... do your research.
Running the Stage kit now, still a few weeks from being home, so I haven't installed my downpipe just yet.
 
365
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18
Buick Ownership
2012 Regal GS
Thread starter #8
Finally installed mine earlier today, took a lot less time than I was expecting. Short of getting bolts for the lower Flange, rest was pretty straight forward. I installed both O2 sensors in the bungs without any extender on the post Cat bung, and no codes so far. Will report back with more mileage.
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EnderWiggin

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Well, got a P0420 code today. Alldata does say with a new cat it can pop a code within the first 100 miles, and to drive at highway speeds for about an hour to help resolve. I suspect it'll probably come back, but we'll see.
 

EnderWiggin

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Not yet, no. Took it for several short (<10 mile) trips, and a longer (~40 mile x2) drive and nothing yet.
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365
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Buick Ownership
2012 Regal GS
Thread starter #15
Well, unplugged my ODB II reader (bluetooth) and the light came on getting dinner last night, another P0420. I should have saved the freeze frame data, but didn't.
 

Evolv0

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2017 Regal GS AWD
#16
Well, unplugged my ODB II reader (bluetooth) and the light came on getting dinner last night, another P0420. I should have saved the freeze frame data, but didn't.
Darn.. that's no good. I guess keep us posted with what goes on. Good luck.
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365
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Buick Ownership
2012 Regal GS
Thread starter #17
Trying the drilled out Spark Plug Defouler method now. Link, installed the defoulers, drove around a little this evening hoping to get a catalyst test, but I couldn't get any codes. I think my ODB2 BT Reader is junk too, and probably doesn't help the car any. I'll report back if anything happens.
 
29
5
3
Buick Ownership
2017 Regal GS AWD
#18
Trying the drilled out Spark Plug Defouler method now. Link, installed the defoulers, drove around a little this evening hoping to get a catalyst test, but I couldn't get any codes. I think my ODB2 BT Reader is junk too, and probably doesn't help the car any. I'll report back if anything happens.
Hmm Interesting, what's the difference between that defouler and a O2 sensor spacer? Won't this just throw a slow response CEL?
 
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