# high flow cat



## sl33pyb (Jan 15, 2007)

*high flow cat!!!UPDATE!!!pics*

today i was peer pressured by my roomate, into as he put it " giving my cat an abortion" because we used a coat hanger blah blah blah. i was wondering if any one has info on or has put a high flow cat on. can vag-com get around the cel if i ever do throw one... which i havnt yet. has any one done anything with their cat? please do not respond if you are going to whine about smog testing, warranty, pollution. now to what i did. any input is much appreciated
1. took off my exhaust
2. cut a coat hanger up 
3. used the coat hanger to "drill" a 1cm hole down the whole cat.
4. no cel ... now for the test drive.

--------------update after talking with someone who knows all about this stuff i decided to bore 4 cm hole all the way through to the flex fipe. first off the exhaust gas smells bad. the car sounds much meaner! power wise i do now notice an increase in top end there is not a sudden loss of power after 5.1k . im very sure of this . on a certain closed course i was able to get to 103 with some one in my car(5000 elv. 55* outside) where as i have made it to 101 at night when it was 20* with no one else in the car
before bore








first small bore only through first cat.








big bore final









_Modified by sl33pyb at 7:28 PM 4-9-2008_


_Modified by sl33pyb at 7:34 PM 4-9-2008_


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## sl33pyb (Jan 15, 2007)

*Re: high flow cat (sl33pyb)*

well i cant say i notice a power increase... 1 -2 hp maybe who knows. but there must be more as part of the cat is gone. you can def. i can hear back fires on a warm cat now... before only on a cold cat. ez messy boardum mod.


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## KampfGTI (Mar 28, 2007)

i know my friend with his 1.8t has run hiflow cats before...always a CEL light after a couple months.....back when i had my SS camaro, we used o2 simulators to delete the rear sensors, or programming to delete the ecu's reading of them


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## elf911 (Jul 27, 2007)

be careful with just putting a 1cm hole thru your cat, its a matrix of ceramic cells which after the hole is made can further break up and cause pieces to come out of your exhaust and/or get stuck at bends in the pipe or your muffler causing blockage. Just gutted my neighbors cats on his E55 nice power gain but we completely removed all of the ceramic material, but missed one piece of metal which flew out about 10 feet from the exhaust also taking my leg with it. Great job but watch for pieces breaking up. As for me when i get my evo header and install i'll be gutting my cat and popping in an old o2 simulator from a friends evo. Have fun with the "new" exhaust bet it sounds meaner too!


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## sl33pyb (Jan 15, 2007)

thanks for the input . i need to find a o2 simulator now. i dont have any mufflers lol. i was also going to look into software to just not even check the second o2 sensor which would be nice


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## Audi4u (Jun 29, 2002)

*Re: (sl33pyb)*


_Quote, originally posted by *sl33pyb* »_thanks for the input . i need to find a o2 simulator now. i dont have any mufflers lol. i was also going to look into software to just not even check the second o2 sensor which would be nice

It can be done.


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## sl33pyb (Jan 15, 2007)

UPDATE top


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## MarcCyberWiz (Jan 4, 2005)

*Re: (Audi4u)*

Sweet I wanna do this










_Modified by MarcCyberWiz at 11:49 PM 4-9-2008_


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## Audi4u (Jun 29, 2002)

*Re: (MarcCyberWiz)*

Thats what its all about. http://****************.com/smile/emthup.gif to the guys that do it, not talk about doing it.


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## whatsyourbeef (Jan 2, 2007)

*Re: high flow cat!!!UPDATE!!!pics (sl33pyb)*

Why don't you just replace your OEM cat with a true high flow model, there are several out there. The best imo is the MetalCat brand, a 200 cell per inch metal substrate cat with over 500 cfm flow capacity. Our stock engine flows under 200 cfm wide open. Even with a monster turbo it won't flow any where near the capacity of the MetalCat. Our stock cat is a 3 way, the MetalCat is a 3 way. So, just replace the OEM cat. especially if you are planning to bypass or shunt you existing sensors. These cats are EPA and Carb approved. here is a website...http://www.justsr.com/new-products/metalcat-catalytic-converters.html?Itemid=1 Also check this out if you want to bypass your sensors...http://zero-signal.org/o2/O2bypass.html.htmgood luck


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## KampfGTI (Mar 28, 2007)

^those links don't work


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## sl33pyb (Jan 15, 2007)

thanks man ive been looking for a high flow cat for our car. this gaping hole is working out great for now but if things change ill get 1.i love the new top end!


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## whatsyourbeef (Jan 2, 2007)

*Re: (sl33pyb)*

those aren't links just addresses, so, copy and paste...


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## KampfGTI (Mar 28, 2007)

yea i tried the last one and got nothing, 404


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## whatsyourbeef (Jan 2, 2007)

*Re: (KampfGTI)*

http://zero-signal.org/o2/O2bypass.html.htm try this.....


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## sl33pyb (Jan 15, 2007)

UPDATE!!! my mpg has gone from 20-21 to 23-25 and im not going any slower. carbon monoxide fumes have also gone from 0 to more... COOL


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## BlackRabbit34 (Jun 2, 2007)

*Re: (sl33pyb)*


_Quote, originally posted by *sl33pyb* »_UPDATE!!! my mpg has gone from 20-21 to 23-25 and im not going any slower. carbon monoxide fumes have also gone from 0 to more... COOL

Good job melting the iceburgs giving us more spring water







, bad job on gas mileage...I drive regular, don't speed, but drive normal, and I get 27-29


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## sl33pyb (Jan 15, 2007)

i speed. its in my blood... i cant help it... ive gone double every speed limit(yes even 80 in texass) in the US minus the montana autobahn. no accidents or speeding tickets......BACK TO THE TOPIC


_Modified by sl33pyb at 9:07 PM 5-16-2008_


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## BlackRabbit34 (Jun 2, 2007)

*Re: (sl33pyb)*

Wow I officially hope your exhaust exploded while your driving, and the shards from your cat get stuck in your anus, where I think they already are


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## markfif (Oct 25, 2007)

why did u only cut out a bit? i took my downpipe out and get ride of the cat completely.


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## sl33pyb (Jan 15, 2007)

but dont you have a cel now mark?? if you don't, ill go gut it right now. i don't have a cel at the moment


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## rental_metard (Jul 17, 2006)

CEL's are what makes vw's vw's. Anyone know if you can make a change in vagcom so only important CELs come on?


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## markfif (Oct 25, 2007)

yessum i do have an amazing CEL. but i have unitronic work on a downpipe tune for our cars. they made the prototype 2.5 tiptronic tune of my ecu and now they are making their downpipe tune off of my car as well







.
im thinking about putting in some o2 extenders to get rid of the CEL for now though. it does get a little pesky.


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## rangerbrown (Jul 12, 2007)

guted mine some time ago, the cel only comes on when cruiseing, and i clear it on the go with my scanguage gaget. nice pops at shifts when cold but other than that no real change.
mpg or performance wise and im tuned. plan to reinstall one here when i get my car bag out of sc and get my duty station were ever that may be. good call on the link above may try that when i get the chance.


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## sl33pyb (Jan 15, 2007)

*Re: (rangerbrown)*

what is this scanguage gaget you speak of?


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