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View Full Version : So I am going to make my own cat pipe...


Xise
12-13-2009, 12:08 AM
Ok so here is the deal, I am up for inspection this month, just got my cracked windsheild taken care of today, next is tires then finally I need a new cat.

Soooo.....as opposed to speding upwaqrds of $300 on a high flow cat I think i am going to make my own pipe and weld some flanges on. Since the stock ct of the RS up until 05 have an abrupt bend right at the start of the cat section what I was planning on doing was grabbnig some cheap ass ebay headers for a wrx and running a more striaght section of pipe from the wrx header to the midpipe and have a cat be somewhere near the front of that pipe so I can use my stock o2 sensor and not need to extend it.

my question is, does the 02 sensor need to be before or after tha converter? I really need to get an emissions sticker otherwise I would just say screw theconverter and run a straight pipe....I am going to have a stromung catback soon so I think the cat section would help eliminate some of the rasp and act almost as a resonator...any thoughts on the matter...fittiment issues?

oh yeah BTW this was the cat i was looking to get http://cgi.ebay.com/ebaymotors/MagnaFlow-HI-Flow-Converter-2-25-Round-Single-O2-53035_W0QQcmdZViewItemQQhashZitem563795052aQQitemZ 370299700522QQptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAc cessories

along with these headers http://cgi.ebay.com/ebaymotors/02-03-04-05-06-Subaru-WRX-STI-header-manifold-4-2-1-New_W0QQcmdZViewItemQQhashZitem3a55be7554QQitemZ25 0546648404QQptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAcce ssories

LMK what you think...I think it will be fairly easy to get this fitted tack welded and then finished up ceramic coated and installed. I know people have done something similar to this so feel free to chime in and let em know whats up

CTATV
12-13-2009, 02:02 AM
sounds good to me meng

Seraphinwolf
12-14-2009, 02:59 AM
There is one O2 before and one after the cat. One reads for the ECU to calculate airfuel ratios so is before any cats, the other which I'm sure is the one you are talking about is behind the cat for emissions.

Seraphinwolf
12-14-2009, 03:03 AM
BTW. thanks for finding a highflow cat! I WANTS FOR SVX! Need to get rid of bottle necks through out the whole car eventually.

subaru_crazy
12-14-2009, 12:42 PM
is your rs turbo if not thats a turbo header for wrx/sti it wouldnt work on a n/a car.

method
12-14-2009, 02:56 PM
Look at Vibrant Performance...I bought one of their high flow metal substrate cats, they are ~ $100

Bu11dogg2
12-14-2009, 03:19 PM
High flow cats may throw a CEL in your car!

I'd poke around and find a used exhaust with good cats for inspection purposes :)

Seraphinwolf
12-14-2009, 04:38 PM
is your rs turbo if not thats a turbo header for wrx/sti it wouldnt work on a n/a car.

Turbo headers bolt right up. He's making a fresh cat pipe to fit between the exhaust manifold and the catback.

Seraphinwolf
12-14-2009, 04:42 PM
High flow cats may throw a CEL in your car!

I'd poke around and find a used exhaust with good cats for inspection purposes :)

On RS25.com we can easily order one from a vendor but it runs $290. Which is hard for lower income peeps or even myself if I don't budgetize for it! Not sure of the exact cat used in that pipe but yes it can pass Cali tests. I see the point though where it might not catch enough for the O2 to register the propper voltage to the ECU.

Bu11dogg2
12-14-2009, 04:58 PM
I really now nothing about N/A tuning.... can the CEL be deleted like with turbo models?

method
12-14-2009, 05:06 PM
I really now nothing about N/A tuning.... can the CEL be deleted like with turbo models?

yes.

Bu11dogg2
12-14-2009, 05:19 PM
It would make sense to me to just have it tuned if you're gonna drop almost $300 on a delete

BG @ BrenTuning
12-14-2009, 10:04 PM
04, can tune and delete the codes for that.

Xise
12-15-2009, 02:13 AM
Yeah but according to Seraphinwolf the 02 bung on the cat I was looking for needs to be after the cat and it looks like the magnaflow one is before :(. The header has it in the right spot and I am pretty sure the cat flows only one way so i am forgced to drill my own O2 bung :) luckily I found this http://cgi.ebay.com/ebaymotors/Oxygen-sensor-bung-KIT-02-o2-nut-dril-fitting-Pre-Curve_W0QQcmdZViewItemQQhashZitem35a5a9138dQQitemZ 230412587917QQptZRaceQ5fCarQ5fParts

either way I am going to do this soon, I hope this doesn't through a code...the cat is meant for a 4.0L motor but that is just according to cali standards...sooo.....hopefully it won't throw codes......either way Bren I will be talking to you soon for a tune, i hope to get some cams first though :D

Xise
02-04-2010, 01:32 AM
well I a, hopefuly going to be welding this together tomorrow...well technically today I guess, I got all my parts together, my schematic drawn up. So tomorrow I take this box of stuff to my uncle's house so we can weld it up and with any luck I will be driving away + a rumlby exhaust note

http://i690.photobucket.com/albums/vv269/XiseTK/DSC01539.jpg

http://i690.photobucket.com/albums/vv269/XiseTK/DSC01540.jpg

wish me luck, hopefully we won't run into any problems, seeing how I am going to be doing this in oh..about 9 hours I should probably get some sleep!

mdungelman
02-04-2010, 07:20 AM
Good luck!