# cat-delete? pros cons.



## AZTDiVR6 (Dec 19, 2008)

im looking into getting an exhaust for my tdi. I think the most expensive part is the downpipe. i think i can get a cat-back or d/p-back made for cheap since i dont need a muffler.
My question, is if i go cat-less, how much is that going to effect my emissions. and will it pass emissions.
and how much do you gain. or do they make a high flow cat. 
whats the best. thanks


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## OttoSchultz (Apr 16, 2004)

The biggest con is that it's illegal. If the inspector looks under the car like he should, it's an instant fail.
Another con is the cost/benefit. What mods have you done to the car? Unless you have a much bigger turbo, huge injectors, and a wild chiptune, you're not going to see much gain from a bigger exhaust. The cat on the TDI is a high flow cat, so just removing it won't do much.
If you're looking for a sound improvement, you may be disappointed. You'll never get the sporty exhaust sound like many gassers have. The turbo absorbs a lot of the sound, but Diesels don't have the same cam profile as a gassers do. The cam is a big factor in the hot rod sound on a gas car.


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## fukengruven1982 (Jan 8, 2005)

*Re: cat-delete? pros cons. (AZTDiVR6)*

The cat is there to help the environment....dont take it off...when I redid the exhaust on my eco diesel..I replaced the cat because Im concerned about polluting in excess..the factory put it there...why mess with it if its for our own benefit?


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## woofie2 (Oct 2, 2003)

*Re: cat-delete? pros cons. (AZTDiVR6)*

Pro-
3-5 MPG gain in fuel mileage. (most highly tuned guys see 4-5 MPG with CAT and muffler delete, not sure about stock but it should increase as well)
sounds cool.
CON-
potential $10k fine if you are found on the road without one.

sidebar-
no major change in emissions, slight increase in NOx output and particulate occupy output but a properly tuned TDI will still pass basic emissions.

_Quote, originally posted by *fukengruven1982* »_The cat is there to help the environment....dont take it off...when I redid the exhaust on my eco diesel..I replaced the cat because Im concerned about polluting in excess..the factory put it there...why mess with it if its for our own benefit?

True, but most Diesels do not get exhaust temperatures high enough to burn off the stuff the cat is designed to reduce.


_Modified by woofie2 at 3:47 PM 5-7-2009_


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## GT TDI Golf (Jan 27, 2003)

*Re: cat-delete? pros cons. (woofie2)*

No real use in getting an aftermarket exhaust system unless you're highly modded. Just replace the rear muffler with a straight pipe. Magnaflow makes a highflow Cat. Checkout TDIparts.com IIRC they're about $150. Running a TDI with no cat or muffler is pretty loud to me. Plus more of a diesel smell. Mine has a cat and resonator and has a great sound. No emissions here in AL either


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## AZTDiVR6 (Dec 19, 2008)

*Re: cat-delete? pros cons. (woofie2)*


_Quote, originally posted by *woofie2* »_
sidebar-
no major change in emissions, slight increase in NOx output and particulate occupy output but a properly tuned TDI will still pass basic emissions.

cool so not too much evironmental damage prob. still alot less than a vr6 even with the cat.
im not modded yet, but i know once i do ill need an exhaust. so i figured i would do that first. i know the 1.8ts need a new d/p once you mod them or it will overheat the turbo. at least thats what they say.
really for now i just want it to sound like the ones on youtube.
http://www.youtube.com/watch?v...lated








i like this one
http://www.youtube.com/watch?v...annel


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## OttoSchultz (Apr 16, 2004)

You'll get pretty close to that sound by just doing a "mufflerectomy". Which is basically just cutting the muffler off and welding in a section of pipe to make the exhaust exit behind the bumper.
There are lot's of chipped and nozzled TDIs running on the stock exhaust/downpipe. You could always install an EGT gauge to monitor exhaust temps.
What nozzles/chiptune are you planning to get? There's a lot of good info in the performance section on TDIclub. I still recommend holding off on the exhaust until you chip, nozzle, and clutch it.


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## AZTDiVR6 (Dec 19, 2008)

*Re: (OttoSchultz)*

ill probably do a mufflerectomy then or something similar, just to hold me off untill i get chipped.

_Quote, originally posted by *OttoSchultz* »_ What nozzles/chiptune are you planning to get? There's a lot of good info in the performance section on TDIclub. I still recommend holding off on the exhaust until you chip, nozzle, and clutch it. 

im not sure what nozzles to get, i guess it depends on the chip. i dont want alot of smoke.
ive been doing research and have lots of questions. like the g60/vr6 clutch. i just installed wietec suspension today but i think it may be a little low in the front.
I would like to do a revo chip tune, because there is a shop in phoenix that does it. but i dont know if its as good as the others. i havent found much info on the revo. ive read alot of good about rocket chip. i know the revo is awesome on a 1.8t. day and night.


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## vwjon21 (Jan 17, 2004)

tdclub can solve all ur problems


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## GT TDI Golf (Jan 27, 2003)

*Re: (vwjon21)*

I would look at the chip tuners than specialize with TDI's. They can tune you for more upgrades down the road like turbos, meth inj, etc. My 2 cents


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## woofie2 (Oct 2, 2003)

*Re: (OttoSchultz)*


_Quote, originally posted by *OttoSchultz* »_ I still recommend holding off on the exhaust until you chip, nozzle, and clutch it.
 Oh, Why, it sounds tougher... I got many "What all have you done to your car?" at gatherings and meetings, because of my mufflerectomy.
when I replied, "It's Stock" guys were like no way, then at TDI gatherings, they were like "dammm, I need to do that to mine"
It's a cheap way to get a little more head turning off the turbo noise.


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## dieselwagen (Jun 7, 2008)

*Re: (woofie2)*

chipping is one stealth upgrade.
leave cat alone unless you know for sure your engine don't need it emission-wise.


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## G60ING (Jun 27, 2000)

*Re: cat-delete? pros cons. (AZTDiVR6)*

In Virginia some of the same shops that say its illegal to remove a cat on a gas car have suggested that I remove the cat on my diesel


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## woofie2 (Oct 2, 2003)

*Re: cat-delete? pros cons. (G60ING)*


_Quote, originally posted by *G60ING* »_In Virginia some of the same shops that say its illegal to remove a cat on a gas car have suggested that I remove the cat on my diesel
















According to the EPA-
only Diesels put on the road after January 2007 need to have a catalytic converter...
http://www.epa.gov/otaq/highwa...7.pdf


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## KubotaPowered (Jan 27, 2005)

*Re: cat-delete? pros cons. (AZTDiVR6)*

They looked for one when I ran mine through emissions down here in Pima county. I have my cat flanged in my Eurojet turbo back exhaust, I just take it back out when emissions is over and replace it with a straight pipe.


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## OttoSchultz (Apr 16, 2004)

_Quote »_According to the EPA-
only Diesels put on the road after January 2007 need to have a catalytic converter...

But if the car was originally equipped with a cat, then it's require to have it. 


_Modified by OttoSchultz at 11:34 AM 5-17-2009_


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## DesuL (Feb 25, 2003)

*Re: (AZTDiVR6)*


_Quote, originally posted by *AZTDiVR6* »_ill probably do a mufflerectomy then or something similar, just to hold me off untill i get chipped.

im not sure what nozzles to get, i guess it depends on the chip. i dont want alot of smoke.
ive been doing research and have lots of questions. like the g60/vr6 clutch.


The G60/VR6 (stock) is what I put in about 6 months ago. It honestly took a while to get used to the clutch feel after that. I am glad I did not go with anything more then the stock VR clutch or I would hate life. I live in Seattle with huge hills and grew up driving them but I still pop it sometimes when not paying attention. The combo feels great and spools the VVT turbo up FAST so its a very strange feel. 
I would go with Rocketchip as they are proven TDI tuned chips. Also if you do a DG EGR delete I hear they have a fix for the CEL that removing your EGR will throw. 
Running a cat no big deal. I have a cat but no muffler, I like a bit of sound without it drowning out anything or attracting attention. In AZ i would stick with the laws as I hear they throw the book at you for lots of stuff. Deleting a cat would equal 3 less burgers a week as far as performance. Or maybe cleaning your car out lol 
Good luck


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## OttoSchultz (Apr 16, 2004)

*Re: (DesuL)*


_Quote »_The G60/VR6 (stock) is what I put in about 6 months ago. It honestly took a while to get used to the clutch feel after that. I am glad I did not go with anything more then the stock VR clutch or I would hate life.

That's interesting. I went with a South Bend Stage I with a 21lb solid flywheel. It's their version of the G60/VR6 clutch. I was surprised that the pedal feel was slightly lighter, but it didn't take too long to get accustomed to it.


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## DesuL (Feb 25, 2003)

*Re: (OttoSchultz)*


_Quote, originally posted by *OttoSchultz* »_
That's interesting. I went with a South Bend Stage I with a 21lb solid flywheel. It's their version of the G60/VR6 clutch. I was surprised that the pedal feel was slightly lighter, but it didn't take too long to get accustomed to it.

7 LBs is alot when its close to 1/3 (or exactly 1/3) of the FW you are running. It is a very different feel and that is not just my opinion, its held with others that have driven the car. Also gotta remeber that in Seattle we have a ton of hills and its a totally diff driving environment.
Your 21lb is only 3 lbs lighter then what I pulled out of my car so I would not even think of it as a performance upgrade. its stronger maybe but its more aimed at daily drivers. I sacrifice some drive-ablity to get my turbo to spool faster with downshifts. I don't commute so I just do whatever I want really. Also (and could be wrong) but less rotational mass on the crank will let the engine spin smoother and increase the engine efficiancy. I am only basing that on logic and physics...


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## AZTDiVR6 (Dec 19, 2008)

*Re: (DesuL)*

i think im going to go RC, i rode in KubotaPowered's. that and other upgrades. very impressive. 300+ lbs tq. i think. im not expecting that much but 90hp is getting old.

_Quote, originally posted by *DesuL* »_Running a cat no big deal. I have a cat but no muffler, I like a bit of sound without it drowning out anything or attracting attention. In AZ i would stick with the laws as I hear they throw the book at you for lots of stuff.
Good luck

were pretty much good, as long as you have current tags and all your lights. 
im sure they dont even know know what a catalytic converter is. its not like california. dont they have to go back through emissions every time they add an aftermarket part, and get a sticker.

_Quote, originally posted by *DesuL* »_Deleting a cat would equal 3 less burgers a week as far as performance. Or maybe cleaning your car out lol 
Good luck

that is exactly how i think. put it in a prespective that i understand. but wouldn't it equal three more burgers. +3 or so mpg. 



_Modified by AZTDiVR6 at 3:07 PM 5-18-2009_


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## OttoSchultz (Apr 16, 2004)

_Quote »_7 LBs is alot when its close to 1/3 (or exactly 1/3) of the FW you are running. It is a very different feel and that is not just my opinion, its held with others that have driven the car. Also gotta remeber that in Seattle we have a ton of hills and its a totally diff driving environment.
Your 21lb is only 3 lbs lighter then what I pulled out of my car so I would not even think of it as a performance upgrade. its stronger maybe but its more aimed at daily drivers. I sacrifice some drive-ablity to get my turbo to spool faster with downshifts. I don't commute so I just do whatever I want really. Also (and could be wrong) but less rotational mass on the crank will let the engine spin smoother and increase the engine efficiancy. I am only basing that on logic and physics...

21lbs is the stock flywheel weight, IIRC. The car was my daily driver, so it needed to be durable but also handle the RCII and Sprint 520s.


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## SilverSleeper05 (Oct 28, 2009)

*Re: cat-delete? pros cons. (woofie2)*

Hey is your 2-4 mpg accurate from just a high flow cat? Im gator tuned on my 05, is it safe to assume i would see the same results?
thanks


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## crapWagen (Oct 12, 2015)

OttoSchultz said:


> The biggest con is that it's illegal. If the inspector looks under the car like he should, it's an instant fail.
> Another con is the cost/benefit.


Guess what? Not everybody lives where YOU DO. Ergo, it might be legal for different posters depending on their location. I'm fuken sick of seeing snobby ass passive aggressive posts (usually by Californians) that try to mislead others, just because THEY aren't allowed to do something where THEY are, because THEY keep reelecting fascists like Barbara Blockhead, Diane Frankenstien, etc




fukengruven1982 said:


> The cat is there to help the environment....dont take it off...when I redid the exhaust on my eco diesel..I replaced the cat because Im concerned about polluting in excess..the factory put it there...why mess with it if its for our own benefit?


News flash. Plants need nitrogen compounds to live. What do you think fertilizer is? Fact: the cats destroy nitrogen compounds that are benevolent or at very least harmless, unless you live in a highly urban environment. 



GT TDI Golf said:


> No real use in getting an aftermarket exhaust system unless you're highly modded. Just replace the rear muffler with a straight pipe. Magnaflow makes a highflow Cat. Checkout TDIparts.com IIRC they're about $150. Running a TDI with no cat or muffler is pretty loud to me. Plus more of a diesel smell. Mine has a cat and resonator and has a great sound. No emissions here in AL either


Yeah, most afermarket exhausts are a complete ripoff. Just get a HF tube bender, some pipe, a gas torch and some brazing rods and go to town. 



G60ING said:


> In Virginia some of the same shops that say its illegal to remove a cat on a gas car have suggested that I remove the cat on my diesel


Virginia is a fascist state. It's a FELONY to have your emissions sticker missing. Anyone that has access to the *outside *of your vehicle can vandalize/remove that sticker. YOU get charged with the FELONY. Neat eh?


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## Volkswagens-for-life (Jun 24, 2013)

Sound is pretty cool on straight piped tdi's, but certainly not loud. It will never be loud; small engine plus a turbo = quiet ride. You can definitely tell the TDI a small engine when you put an exhaust on it.


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## MXTHOR3 (Jan 10, 2003)

SilverSleeper05 said:


> Hey is your 2-4 mpg accurate from just a high flow cat? Im gator tuned on my 05, is it safe to assume i would see the same results?
> thanks


You aren't going to see a 2-4 mpg gain by removing the cat. You'll gain maybe 1hp? As for a mileage increase, pretty much nothing.


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## Volkswagens-for-life (Jun 24, 2013)

For the ENTIRE downpipe back, I could see 2-4mpg maybe. Maybe.


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## MXTHOR3 (Jan 10, 2003)

Volkswagens-for-life said:


> For the ENTIRE downpipe back, I could see 2-4mpg maybe. Maybe.


On a stock car with stock tuning? That's wishful thinking.


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## thesilversurferII (Sep 26, 2012)

MXTHOR3 said:


> You aren't going to see a 2-4 mpg gain by removing the cat. You'll gain maybe 1hp? As for a mileage increase, pretty much nothing.


 I am sorry to say but you are wrong,If you do a egr/dpf delete and you do the right tune you can easily see a 2-4 mpg gain and you got to think about a diesel it not hp but tq. Toque is what moves a diesel not hp, hp just keeps it going.Why do you think all these big diesel trucks Dodge,Ford and GMC run egr deletes and are catless and run these tunes and make a ton of toque and horsepower, plus an egr will kill a diesel easily. Do your research on diesel power before you talk hp/tq gains ok


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## Volkswagens-for-life (Jun 24, 2013)

thesilversurferII said:


> I am sorry to say but you are wrong,If you do a egr/dpf delete and you do the right tune you can easily see a 2-4 mpg gain and you got to think about a diesel it not hp but tq. Toque is what moves a diesel not hp, hp just keeps it going.Why do you think all these big diesel trucks Dodge,Ford and GMC run egr deletes and are catless and run these tunes and make a ton of toque and horsepower, plus an egr will kill a diesel easily. Do your research on diesel power before you talk hp/tq gains ok


Learn what a pump duse is before you start talking about DPF's and 'dem gains'. Bro.


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## thesilversurferII (Sep 26, 2012)

Volkswagens-for-life said:


> Learn what a pump duse is before you start talking about DPF's and 'dem gains'. Bro.


 um yea let see here last i checked pump duse was used in a 2004-2006 which is the 1.9 turbo diesel and all 2009+ diesel vw use what is call common rail
l 
2004-2006 TDI
These are all pumpe duse (PD), a new type of direct injection. It had been used in European TDI for a while before coming to North America. Check out the cosmetic differences between mk4 pumpe duse and non-pumpe duse Jetta if you're having trouble identifying what car you have (2004-2005 Passat TDI, BHW engine, and Touareg V10 TDI are all PD). The change to PD was to meet newer emissions standards.

PD engines have significant mechanical differences from the earlier non-pumpe duse cars. 2004-2006 4th generation cars use the BEW engine (2004-2006 Golf/New Beetle) and 5th generation cars use the BRM engine (2005.5-2006 5th generation Jetta TDI). The difference is because the Jetta changed over to the 5th gen in 2005.5. All PD use a low pressure electric fuel pump (about 6-8 psi) in the fuel tank, something that earlier TDI did not. See the buying guides in the FAQ for more differences.

2009 + 4 cylinder TDI
These use common rail engines which saw major changes. Common rail runs cleaner and more powerful but since it's a new technology, has had some reliability and teething issues in both diesel and gasoline cars. The change to common rail was to meet 50 state and Euro emissions standards. Because of greater advertising/awareness, supply, and higher fuel prices, these TDI are by far, the most common.

While the 2009-2010 Jetta sedan uses the same body as the 2005.5-2006 Jetta, it has a completely different engine/transmission and emissions control system. The engines were the CJAA and CBEA for North America. Again, body style does not necessarily follow engine model for all TDI. The 2010 Audi A3 is the first TDI passenger car that Audi has sold in North America (they were sold in Europe for years). It uses the same common rail engine found in the newest Golf/Jetta TDI.

The 2012 Passat TDI uses what I call "version 1.5 " of this generation of common rail engines. While retaining many basic characteristics, the CKRA engine on the Passat uses a different fuel pump, fuel injectors, turbo, and air-water intercooler like the V2.0 mk7 engines. Fuel pump failure is not yet noticeable except a few random failures but long term reliabilty after high miles is still unknown.

sorry no pump duse BRO I am not stupid


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## MXTHOR3 (Jan 10, 2003)

thesilversurferII said:


> I am sorry to say but you are wrong,If you do a egr/dpf delete and you do the right tune you can easily see a 2-4 mpg gain and you got to think about a diesel it not hp but tq. Toque is what moves a diesel not hp, hp just keeps it going.Why do you think all these big diesel trucks Dodge,Ford and GMC run egr deletes and are catless and run these tunes and make a ton of toque and horsepower, plus an egr will kill a diesel easily. Do your research on diesel power before you talk hp/tq gains ok


Huh? There is no DPF on the ALH or PD cars that VW offered here.. DPFs started in '09 with the CBEA. A CAT and a DPF are completely different things, the new CR engines get some great gains by removing the DPF, the older PD and rotary pump cars gain zero when removing the CAT.

As for EGR deletes, people run them to keep their intake tracts cleaner, nothing more. There are no power gains or mpg gains from doing this.. If you knew anything about diesels, you'd realize this.

Also, we appreciate the info you decided to copy/paste from myturbodiesel, lol. If you've got any of your own thoughts, please feel free to share.


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## Volkswagens-for-life (Jun 24, 2013)

MXTHOR3 said:


> Huh? There is no DPF on the ALH or PD cars that VW offered here.. DPFs started in '09 with the CBEA. A CAT and a DPF are completely different things, the new CR engines get some great gains by removing the DPF, the older PD and rotary pump cars gain zero when removing the CAT.
> 
> As for EGR deletes, people run them to keep their intake tracts cleaner, nothing more. There are no power gains or mpg gains from doing this.. If you knew anything about diesels, you'd realize this.
> 
> Also, we appreciate the info your decided to copy/paste from myturbodiesel, lol. If you've got any of your own thoughts, please feel free to share.


I didn't have the patience. Thank you.


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## MXTHOR3 (Jan 10, 2003)

I'm patiently waiting to hear about the DPF I've got on my BEW.


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## damac2004 (Jun 18, 2010)

i never even thought about this but lets say you retrofit an older tdi into an older chasis and were going to redo the exhaust like me.

after messing with a few cars i have learned that i absolutely want to stop the noise, im sick of the chopped off and gutted sounds after probably the first day. gives me a headache and i don't want to turn heads.

can i just put a high flow cat on after the downpipe to help the environment and possibly act as a resonator and then choose another diesel muffler at the end and hopefully kill the noise?


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## MXTHOR3 (Jan 10, 2003)

Yup, a cat would definitely help with the drone. You could also run a small resonator as well.


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## Volkswagens-for-life (Jun 24, 2013)

damac2004 said:


> i never even thought about this but lets say you retrofit an older tdi into an older chasis and were going to redo the exhaust like me.
> 
> after messing with a few cars i have learned that i absolutely want to stop the noise, im sick of the chopped off and gutted sounds after probably the first day. gives me a headache and i don't want to turn heads.
> 
> can i just put a high flow cat on after the downpipe to help the environment and possibly act as a resonator and then choose another diesel muffler at the end and hopefully kill the noise?


Yes, absolutely.


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