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    Thread: What's the View Here on Catless Downpipes/Cat Deletes?

    1. Member
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      05-11-2012 05:06 PM #26
      when i upgraded my 84 gti to a bigger exhaust (for 2" to 2 1/4") i didnt want to spend the money on a bigger cat, and since in pa at the moment any car pre 86 is visual emissions only, all i have to do is have the shell of the cat around the pipes for it to pass. just nneed to know its there, doesnt have to be functioning

    2. Member vasillalov's Avatar
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      05-11-2012 05:07 PM #27
      The biggest benefits are for FI cars, particularly turbo cars. Lack of catalytic converters improves spooling time, response time and also reduces EGTs which helps A LOT.

      On BMW N54 engine the catless downpipes will give you easy 40-60 whp and 40-50 wtq with proper tuning.

      BTW, I just passed Illinois emissions testing last week.

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      05-11-2012 05:09 PM #28
      Quote Originally Posted by vasillalov View Post
      The biggest benefits are for FI cars, particularly turbo cars. Lack of catalytic converters improves spooling time, response time and also reduces EGTs which helps A LOT.

      On BMW N54 engine the catless downpipes will give you easy 40-60 whp and 40-50 wtq with proper tuning.

      BTW, I just passed Illinois emissions testing last week.
      on cars without a keychain turbo, the gains really can be pretty massive.

      yes even on modern cars.
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    4. Member vasillalov's Avatar
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      05-11-2012 05:11 PM #29
      As a second note: I wonder how different would be the emissions of modern day direct injection motors compared to port injected motors and even carbed motors if the catalytic converters are not present?... I'd venture a guess that the DI motors will produce marginally less emissions than other motors simply because the fuel gets better atomization and more efficient burn is achieved.

    5. Member vasillalov's Avatar
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      05-11-2012 05:12 PM #30
      Quote Originally Posted by x_GTI_x View Post
      on cars without a keychain turbo, the gains really can be pretty massive.

      yes even on modern cars.
      Haha yeah, the N54 does have pretty small turbos indeed. And this is the reason why so much power is made when uncorked.

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      05-11-2012 05:15 PM #31
      Get some nice downpipes, not those ssac ones, or atleast wait til their 3" comes out. JB weld a cat cover over the test pipes, and get the rear 02's coded out. Perfect.

      Typical righteous Car Lounge response


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      05-11-2012 05:17 PM #32
      Quote Originally Posted by vasillalov View Post
      The biggest benefits are for FI cars, particularly turbo cars. Lack of catalytic converters improves spooling time, response time and also reduces EGTs which helps A LOT.

      On BMW N54 engine the catless downpipes will give you easy 40-60 whp and 40-50 wtq with proper tuning.

      BTW, I just passed Illinois emissions testing last week.
      I have "heard" from a "friend" with an N55 engine with a catless DP, that hte gains are pretty huge and spool-up times are massively decreased.

      But that same friend doesn't really like the smell, and feels a bit bad about the environment.
      I TCL.

    8. Member greatfox's Avatar
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      05-11-2012 05:17 PM #33
      I ran catless on my GTI (when I had it) and currently on my S2000. But since I don't (or didn't in the case of my GTI) drive more than 2,000 miles per year with them, I don't feel guilty. My DD has a cat and it will stay that way.

      Edit: The reason why I do it on my S2000 is twofold. 1) It reduces the drone of my single 70mm exhaust (and makes the tone sound a lot better) 2) I gained around 10 hp (which is huge on an S2000)

      The way I see it is if a sport bike doesn't need a cat, then my S2000 doesn't either.
      Last edited by greatfox; 05-11-2012 at 05:22 PM.
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      05-11-2012 05:24 PM #34
      Quote Originally Posted by AggvGtivr6 View Post
      Get some nice downpipes, not those ssac ones, or atleast wait til their 3" comes out. JB weld a cat cover over the test pipes, and get the rear 02's coded out. Perfect.

      Typical righteous Car Lounge response



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      05-11-2012 05:26 PM #35
      Screw the environment. Do it for the fire!


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      05-11-2012 05:40 PM #36
      TO those who think HFCs or test pipes do not add to performance, you are misinformed. It does depend on the car and how restrictive the stock cats were, but most late model cars always experience a gain in exhaust flow, and these performance improvements are heavily documented.

      Also, it is not just for FI cars. On the G37, HFCs are dyno proven as one of the single most gaining modifications with about 20whp improvements over stock. There are two of them, so that's one of the reasons.

      Contrary to popular belief, most also see improvements in MPGs.

      That being said, of course it will let more CO2 out of the car. However, the % of people doing this is so small, I doubt there is any significant scientific detriment on a large scale, especially not enough to offset the yearly decrease in nationwide emissions with the advent of more efficient and less polluting cars taking to the roads each day. I'm not saying it's OK, just that it's not this horrid thing a lot of people may make it out to be.

      What you all should be worried about is CHINA. Talk about pollution.

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      05-11-2012 05:42 PM #37
      I have no cat on my rabbit. I *may* drive it several hundred miles a year. Berate me if you may, my header setup somewhat precludes it.
      Dave

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      05-11-2012 05:45 PM #38
      More power, faster spool, popping, gurgling, and turbo jet noises through the exhaust..... what's not to love?

      I might be alone on this one, but I love the smell of a catless exhaust, especially after decel through the gears.

      My wife's Sonic will see 10x the miles that the Mustang will in a year, so... eh.

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      05-11-2012 05:50 PM #39
      I have a catless setup on the GT-R. Sue me. The benefits far outweigh the negatives and the car doesn't get driven that much anyway.

      I have a HFC on the Acura, which sees 15k+ miles a year. The headers came with a test pipe, and I had an aftermarket HFC welded in. Toned the noise down some and the car is happy with no CELs or anything.
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      05-11-2012 05:56 PM #40
      I have a catless DP on my GTI.

      But i live in Alberta, ****ing up the environment is what we do..
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      05-11-2012 05:57 PM #41
      Inb4GermaniuM... Lol
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    17. 05-11-2012 05:58 PM #42
      This owner has yet to do a cat delete.


    18. Member S0RRY's Avatar
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      05-11-2012 06:02 PM #43
      Quote Originally Posted by jepva View Post
      What you all should be worried about is CHINA. Talk about pollution.
      welp, since china's polluting, we might as well just give up! Love reading some people's justifications for doing selfish things.

    19. Member vasillalov's Avatar
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      05-11-2012 06:23 PM #44
      Quote Originally Posted by jepva View Post
      That being said, of course it will let more CO2 out of the car. :
      Actually, the CO2 emissions remain the same. It is the emissions of particulate matter, un-burnt hydrocarbons. nitrogen oxide and sulphur that does not get suppressed by removing the catalytic converters.

    20. Member cockerpunk's Avatar
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      05-11-2012 06:28 PM #45
      Quote Originally Posted by S0RRY View Post
      welp, since china's polluting, we might as well just give up! Love reading some people's justifications for doing selfish things.
      you know, i understand the science behind climate change, i understand the effects of man made carbon gasses on the radiation absorption of the atmosphere, i do. i vote democrat, i even freaking recycle.

      but really, there are battles to fight, and there are battles that arnt worth fighting. and you know, im not going to feel guilty for by passing the cat on my classic car. sorry.

      its just not an issue. really.
      Quote Originally Posted by kwik!gti
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    21. Member patrickvr6's Avatar
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      05-11-2012 06:40 PM #46
      Quote Originally Posted by xtravbx View Post
      Yeah... catalytic convertors usually don't "go wrong."


      Cats fail all the time and they are a big reason why a good number of late model cars are scrapped or traded in for something new.

      I just spent $1400 and 12 hours of my time replacing the cats on my 325i because I have to pass emissions with it. If I didn't get tested I would bought straight headers and not worried about it.

      Quote Originally Posted by S0RRY View Post
      welp, since china's polluting, we might as well just give up! Love reading some people's justifications for doing selfish things.

      Read this and then get all sanctimonious about someone choosing not to run cats.

      http://www.gizmag.com/shipping-pollution/11526/
      Last edited by patrickvr6; 05-11-2012 at 06:43 PM.

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      05-11-2012 07:31 PM #47
      Quote Originally Posted by cockerpunk View Post
      you know, i understand the science behind climate change, i understand the effects of man made carbon gasses on the radiation absorption of the atmosphere, i do. i vote democrat, i even freaking recycle.

      but really, there are battles to fight, and there are battles that arnt worth fighting. and you know, im not going to feel guilty for by passing the cat on my classic car. sorry.

      its just not an issue. really.
      I was more mocking his justification than the act itself. I personally don't care if you run cats or not, but nothing annoys me more than logical fallacies.

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      05-11-2012 10:16 PM #48
      Pre-cats can be very restrictive and only provide benafits for 30 seconds of every day... so I'll cave and say you aren't a total douche for removing those but removing the main cats is still a douche move. I went with 3" high flow cats on a 1.8 liter forced induction engine. Massive over kill but they flow fantastically well and my turbo spools up PLENTY fast thank you very much. All while still being kind to the planet we live on.
      ■■■■■■■■■■■■

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      05-11-2012 10:26 PM #49
      Quote Originally Posted by Adam144 View Post
      Screw the environment. Do it for the fire!

      im with this guy, it was a a given to remove the cat with webers or else it would have gotten ruined anyways

    25. 05-11-2012 10:45 PM #50
      if you have a reason to remove it.... IE....diesel, carbs, or FI that is running rich for performance reasons, then yes, if just because you want to add 3 hp. n0o0o0o0o! cats on most modern cars almost have a immeasurable effect on power and will usually get you in huge trouble if caught with out them.

      in the last few years I have owned 3 cars with out them, a carbed rx7 that shoots 3 foot flames (tried one killed it in 3 days), a tuned tdi , running rich enough to kill it so I pulled it before it could, and a car that didint come with one stock. other then that the have or had cats. my miata's cat is worn out, and I plan on upgrading the cat, but the CAR WILL HAVE ONE.
      I'm a certified vw/mazda dealer tech and I run a modification shop on the side.
      02 beetle tdi,00 jetta 2x4, 92 miata,,30 pontiac.

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