Which high flow cat do i get?

[xrobbx03]

Im looking to get the catco high flow. Which one do i get that will support the rear o2 sensor? Is the one with the air tube or are there special ones for that.

 

[DGajre777]

Go to www.roadraceengineering.com and look at their downpipes and 3" high flow cat.

If you don't want to buy a downpipe again, just take your car to an exhaust shop and have them weld a 3" downpipe after the flex and before the rear o2 sensor.

 

[xrobbx03]

what do you mean i wont be able to use my downpipe?

 

[Strm Trpr]

Your profile says that you have an Apex Downpipe.
All of the Apexi downpipes that I know of are Cat Delete downpipes.
If you do have the unmodified Apexi N1 turbo back exhaust system, then you are currently running no catalytic converter.

 

[xrobbx03]

yeah your right i have no cat. But i need to pass emissions and i need my rear o2 sensor. I bought the car with the downpipe on there. So i was looking to get a cat back on there and an o2 sensor. I just didnt know how that all works.

 

[pitbull419]

So your going to have to buy another downpipe and a hi flow cat.
Or try to put one after the cat delete and fab the rest of the exhaust back your self(not a good idea)
So id buy a megan racing down pipe and hi flow cat there the cheapest i belive.

 

[Strm Trpr]

Megan DP's delete the cat just like the Apexi units.
I used to have a 97 GST, and I also had a Megan DP cut and flanged and then had a 3" HF Cat flanged and then I had a custom mandrel 3" non-resonated exhaust to a Megan Turbo Muffler.
Sounded mean as all hell.

Look at this link. http://www.roadraceengineering.com/parts/dp/rredp-2gfwd-options.jpg
Have an exhaust shop hook you up with a similar set-up.
Here's a link to the 3" HF Cats that RRE offers.
http://www.roadraceengineering.com/exhaustparts.htm

Go here, http://www.roadraceengineering.com/flangesandgaskets.htm and look about 2/3 of the way down.
Look for 3" 2-bolt exhaust flanges, and gaskets.
Buy 2 of each if your exhaust shop doesn't carry that size.
The flanges will match up to your Apexi DP and Cat-back.

That's what I did.

I passed emissions here in CA, no problem.

 

[xrobbx03]

I just cant cut out and flange the N1 downpipe and put a cat there?

 

[DGajre777]

I just cant cut out and flange the N1 downpipe and put a cat there?

Sure you can. There are many ways to do it. You could take the your downpipe and have a 3" cat welded in before flange that you it still bolts up to the N1 cat back exhaust.

 

[xrobbx03]

Ok. Last Question where would i have the bung for the o2 sensor put on. Before or after the cat?

 

[DGajre777]

Ok. Last Question where would i have the bung for the o2 sensor put on. Before or after the cat?

You don't need to put another bung for the rear o2 sensor. The Apexi N1 cat back exhaust systems have a bung after the cat.

The only time you will need a third bung is if you want to keep your front o2 (which is in the o2 sensor which is after the turbo and before the downpipe) and if you want to keep your rear o2 sensor (which is after to cat and its ony purpose is to tell the ECU that that cat is working) and if you want to get a wideband o2 sensor for tuning.

Get this - http://www.slowboyracing.com/more.php?id=1466& or something similar, take it to an exhaust shop and tell them to put it in your downpipe. They will cut it before the flange and weld it in there.

I'm sorry for my terrible paintshop skills, but it will end up looking the attached pic.

 

[xrobbx03]

and also i know on FWD the N1 downpipe that the inlet is 2.5" and the outlet is 3" so if i cut a section out of the downpipe is the pipe size going to be 2.5" or 3"

 

[xrobbx03]

You don't need to put another bung for the rear o2 sensor. The Apexi N1 cat back exhaust systems have a bung after the cat.

The only time you will need a third bung is if you want to keep your front o2 (which is in the o2 sensor which is after the turbo and before the downpipe) and if you want to keep your rear o2 sensor (which is after to cat and its ony purpose is to tell the ECU that that cat is working) and if you want to get a wideband o2 sensor for tuning.

Get this - http://www.slowboyracing.com/more.php?id=1466& or something similar, take it to an exhaust shop and tell them to put it in your downpipe. They will cut it before the flange and weld it in there.

Really. I have a Cel of on my car I wonder if my o2 Sensor is just Bad.

 

[DGajre777]

Really. I have a Cel of on my car I wonder if my o2 Sensor is just Bad.

Your CEL is on because the o2 sensor is not detecting the cat (basically).