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Author Topic: Pre-cat. . . . . REMOVED!  (Read 91243 times)

Offline GrayMK5GTI

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Pre-cat. . . . . REMOVED!
« on: January 18, 2012, 01:07:58 pm »
I'd seen a lot of posts on Briskoda forum about people removing the pre-cat from the exhaust downpipe (not to be confused with the normal CAT) and seen some great gains in terms of power and fuel economy (some members reporting a gain of 5MPG). Most people do this themselves by removing the 4 bolts by the turbo, remove downpipe and take a hammer & chisel to the pre-cat. I didnt fancy doing it myself so I booked mine it at my local trusted garage (ABP Motorsport in shavington, Crewe) and they did the work in just under an hour :congrats:

After a bit of ECU - adapting (on the bypass) I'm happy to report the following:

- More turbo sound  :drool:
- slightly deeper exhaust note :smiley:
- faster turbo spool up  :happy2:
- pulls harder in the higher revs  :driver:

So to sum up, it's a win-win for me  :star: I'll report back on the MPG effect at a later date.

I should also point out that this WILL NOT CAUSE YOUR CAR TO FAIL AN MOT! (unless the requirements change again). VW fit it to aid cold-start emissions which isn't tested as part of the uk MOT.

It's worthwhile changing the manifold gasket and the nuts while your doing it (parts are only about £8 from vw)

See here for more info, part no's and photos: http://briskoda.net/forums/topic/197778-pre-cat-removed/


Cheers,

Graeme
« Last Edit: January 18, 2012, 01:12:05 pm by GrayMK5GTI »
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Offline sub39h

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Re: Pre-cat. . . . . REMOVED!
« Reply #1 on: January 18, 2012, 01:10:25 pm »
i'm guessing if you have an aftermarket exhaust, a Milltek or similar, that these don't have pre-cats in anyway?
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Offline GarethB

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Re: Pre-cat. . . . . REMOVED!
« Reply #2 on: January 18, 2012, 01:19:40 pm »
Sounds good Graeme.

depending on whether you remap beforehand, it would interesting to see if you achieve any power gains on JKM's rollers next month
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Offline Tfsi_Mike

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Re: Pre-cat. . . . . REMOVED!
« Reply #3 on: January 18, 2012, 01:21:36 pm »
Quote from: sub39h on January 18, 2012, 01:10:25 pm
i'm guessing if you have an aftermarket exhaust, a Milltek or similar, that these don't have pre-cats in anyway?

My Miltek didnt  :happy2:
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Offline GrayMK5GTI

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Re: Pre-cat. . . . . REMOVED!
« Reply #4 on: January 18, 2012, 01:24:18 pm »
Quote from: sub39h on January 18, 2012, 01:10:25 pm
i'm guessing if you have an aftermarket exhaust, a Milltek or similar, that these don't have pre-cats in anyway?

No mate, standard exhaust. Didn't want to go all out for a full exhaust system with a cambelt change due
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Offline GrayMK5GTI

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Re: Pre-cat. . . . . REMOVED!
« Reply #5 on: January 18, 2012, 01:25:59 pm »
Quote from: GarethB on January 18, 2012, 01:19:40 pm
Sounds good Graeme.

depending on whether you remap beforehand, it would interesting to see if you achieve any power gains on JKM's rollers next month

Funny you should say that, it's booked in at R-Tech on Saturday - should get a dyno run before as a comparison though!  :happy2:
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Offline GarethB

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Re: Pre-cat. . . . . REMOVED!
« Reply #6 on: January 18, 2012, 01:33:21 pm »
ohhh, R-Tech. I've never used them personally, but they've always had a great rep across all the forums.

I'm sure that you'll be happy with the results. Is it just booked in for a map, or are there other goodies in store?

Look forward to seeing how it does on JKMs RR. My car should perform a little better than last time too  :evilgrin:
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Offline GrayMK5GTI

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Re: Pre-cat. . . . . REMOVED!
« Reply #7 on: January 18, 2012, 01:39:33 pm »
Quote from: GarethB on January 18, 2012, 01:33:21 pm
ohhh, R-Tech. I've never used them personally, but they've always had a great rep across all the forums.

I'm sure that you'll be happy with the results. Is it just booked in for a map, or are there other goodies in store?

Look forward to seeing how it does on JKMs RR. My car should perform a little better than last time too  :evilgrin:

Yes I've heard a lot of good things about them, seem to know a lot about the TFSI's and do full diagnostics before the map.

Nah not going in for anything else, just the custom stage one  :happy2:

Yours should be up on last time with the revo map. Have you got any other mods yet?
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Offline GarethB

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Re: Pre-cat. . . . . REMOVED!
« Reply #8 on: January 18, 2012, 02:01:45 pm »
Yes, it should hopefully perform a little better than before.

Got several parts sat waiting to be fitted, but finding the time to fit is tricky - especially being an accountant in january!

Hopefully will have a few bits sorted by 11 February in time for the RR day.
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Offline GrayMK5GTI

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Re: Pre-cat. . . . . REMOVED!
« Reply #9 on: January 18, 2012, 04:36:56 pm »
Quote from: GarethB on January 18, 2012, 02:01:45 pm
Yes, it should hopefully perform a little better than before.

Got several parts sat waiting to be fitted, but finding the time to fit is tricky - especially being an accountant in january!

Hopefully will have a few bits sorted by 11 February in time for the RR day.

Awesome you will have to take me out for a spin!
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Offline vRS_Pagey

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Re: Pre-cat. . . . . REMOVED!
« Reply #10 on: January 18, 2012, 10:35:53 pm »
I was planning this for my vRS (I think I may have contributed to the post on Brisky)  but I got my hands on a used Milltek down pipe with sport cat for a 200 quid........  :party:
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Offline meady

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Re: Pre-cat. . . . . REMOVED!
« Reply #11 on: January 19, 2012, 06:15:44 am »
So ur telling me the golf gti has a pre cat and a main cat? I thought i had goten away from that when i sold my astra :(
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Offline GrayMK5GTI

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Re: Pre-cat. . . . . REMOVED!
« Reply #12 on: January 19, 2012, 07:04:35 am »
Quote from: meady on January 19, 2012, 06:15:44 am
So ur telling me the golf gti has a pre cat and a main cat? I thought i had goten away from that when i sold my astra :(

That's right, at least its easy to remove bud  :grin:
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Offline vRS_Pagey

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Re: Pre-cat. . . . . REMOVED!
« Reply #13 on: January 19, 2012, 10:45:19 am »
Quote from: meady on January 19, 2012, 06:15:44 am
So ur telling me the golf gti has a pre cat and a main cat? I thought i had goten away from that when i sold my astra :(

Yup, the pre-cat filter is located directly after the turbo, so all the hot gases are slamming directly in to a wall!!  It's only there for the European cold emissions test, not a requirement in the UK so no issue with removal!  By getting rid, the gases movement is not as restricted which results in quicker spool up etc.  Obviously the ideal is to change the down pipe which increases diameter, and reduces catalyst material but the pre-cat removal on the OE exhaust is the next best thing.  :wink:
« Last Edit: January 20, 2012, 12:19:20 pm by vRS_Pagey »
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Offline Bogwoppit

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Re: Pre-cat. . . . . REMOVED!
« Reply #14 on: January 19, 2012, 08:22:54 pm »
Thought I'd post up my Briskoda photo on here if it helps:
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