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Model specific boards => Golf mk3 => Topic started by: tobybrennan on 01 August 2009, 18:06

Title: de cat
Post by: tobybrennan on 01 August 2009, 18:06

is this genuine?
and what sort of change would i be looking at, as in sound and power?
much or?


http://cgi.ebay.co.uk/VW-GOLF-MK3-8V-16V-VR6-DECAT-DE-CAT-PIPE-EXHAUST_W0QQitemZ220442738394QQcmdZViewItemQQptZUK_CarsParts_Vehicles_CarParts_SM?hash=item3353693eda&_trksid=p3286.c0.m14
Title: Re: de cat
Post by: tobybrennan on 01 August 2009, 18:07
hmm just saw wont pass MOT with this, so any that will?
Title: Re: de cat
Post by: gtigolfthree on 01 August 2009, 18:21
Keep the cat and stick it back on for the mot. :wink:
Title: Re: de cat
Post by: Mikester on 01 August 2009, 18:23
Just buy a sports cat. Its still high flow, but passes mot. Mine passed the mot on the border line, but still passes ;)

Failing that. With all of the extra power the De-Cat gives you (sarcasm) the police wont be able to catch you when they see you have no mot.
Title: Re: de cat
Post by: tobybrennan on 01 August 2009, 18:27
where sells them? link?

aha, not give you much boost then? talking a couple of brake? or not even that
Title: Re: de cat
Post by: Mikester on 01 August 2009, 18:32
At the end of the day. VW are not retards. They made the exhaust system to be able to cope with the engine.

Upgrading the exhaust flow is good, yes, but unless you mod the engine, its not actually adding much more power than like 1-2bhp really. What you will get is a headache though.
Title: Re: de cat
Post by: tobybrennan on 01 August 2009, 18:32
okay matey, cheers
Title: Re: de cat
Post by: AudiA8Quattro on 01 August 2009, 18:48
De-catting will give a good increase in power, as they are very restrictive.
Title: Re: de cat
Post by: tobybrennan on 01 August 2009, 18:57
stupid question i know, but do all decat pipes fail MOT?
Title: Re: de cat
Post by: gtigolfthree on 01 August 2009, 19:27
Pretty much the emmissions are higher without it.
Title: Re: de cat
Post by: Wayne on 01 August 2009, 20:30
stupid question i know, but do all decat pipes fail MOT?

Yes as you need a cat for the mot.
Title: Re: de cat
Post by: tattyoldvan on 02 August 2009, 11:17
Little bit of thread hijacking but, My mot place says if cat not fitted not cat test, whatever this is is not required, but car will still have to pass the vehicles emissions for that vehicle. however if a car is converted to lpg it is not subject to emissions testing, whether it can run on petrol or not
Title: Re: de cat
Post by: shepgti on 02 August 2009, 11:31
all i can say is dont buy a sports cat as they are stupid money
Title: Re: de cat
Post by: Khare on 02 August 2009, 11:39
all i can say is dont buy a sports cat as they are stupid money
+1, better off slipping the tester a £20 note :grin:
Title: Re: de cat
Post by: christomk3gti on 02 August 2009, 12:18
 :grin:

Title: Re: de cat
Post by: robz on 02 August 2009, 12:33
personally from the experience of having a de cat on the mini i wouldnt bother again!!
complete head ache and 3 months of no mot :shocked: :sad:
would rather have a sports cat but as said they are rip off for the gais ya get!!
Title: Re: de cat
Post by: VW BUSH on 02 August 2009, 20:04
http://www.sportcats.co.uk/product_info.php?cPath=2_104_106_108&products_id=627&osCsid=c8563243c4529b4560ca8bc33cbd27a8

10bhp gain = £250 for S cat and £300 for rest of exhaust
Title: Re: de cat
Post by: shepgti on 02 August 2009, 20:07
http://www.sportcats.co.uk/product_info.php?cPath=2_104_106_108&products_id=627&osCsid=c8563243c4529b4560ca8bc33cbd27a8

10bhp gain = £250 for S cat and £300 for rest of exhaust

complete rubbish and expensive rubbish at that
Title: Re: de cat
Post by: VW BUSH on 02 August 2009, 21:03
http://www.sportcats.co.uk/product_info.php?cPath=2_104_106_108&products_id=627&osCsid=c8563243c4529b4560ca8bc33cbd27a8

10bhp gain = £250 for S cat and £300 for rest of exhaust

complete rubbish and expensive rubbish at that

Very expensive.
Another £500 and you have a VR6
Title: Re: de cat
Post by: Wayne on 02 August 2009, 21:30
Can I add that modern cats don't lose that much, I know someone that fitted a sports car and only gained 2bhp.
Title: Re: de cat
Post by: VW BUSH on 02 August 2009, 21:42
Can I add that modern cats don't lose that much, I know someone that fitted a sports car and only gained 2bhp.
I was taught that only big turbo's realy gained from sports cats/de cat's but that was 13 years ago, sure i will be corrected though
Title: Re: de cat
Post by: Wayne on 02 August 2009, 21:45
Can I add that modern cats don't lose that much, I know someone that fitted a sports car and only gained 2bhp.
I was taught that only big turbo's realy gained from sports cats/de cat's but that was 13 years ago, sure i will be corrected though


Not really sure, you might get a bigger gain on a turbo.
Title: Re: de cat
Post by: boneybradley on 02 August 2009, 21:57
On a turbo car once the gas passes through the turbo it is beneficial to get rid of them as quick as poss while on a n/a car the cat will slow the gas and help compression/efficiency (and if you loose this you'll find the rev range higher you'll gain..maybe a few bhp but it will loose torque!)

remember turbo boost effects compression so after the turbo it won't affect the power
Title: Re: de cat
Post by: VW BUSH on 02 August 2009, 22:05
Can I add that modern cats don't lose that much, I know someone that fitted a sports car and only gained 2bhp.
I was taught that only big turbo's realy gained from sports cats/de cat's but that was 13 years ago, sure i will be corrected though


Not really sure, you might get a bigger gain on a turbo.

I know some N/A cat cars respond well to de cats and sport cats, the MK3 GTI 8v does not seem to gain much from it even with a full SS system behind it, 16v aint much better either but i could'nt comment on the VR
Title: Re: de cat
Post by: VW BUSH on 02 August 2009, 22:09
On a turbo car once the gas passes through the turbo it is beneficial to get rid of them as quick as poss while on a n/a car the cat will slow the gas and help compression/efficiency (and if you loose this you'll find the rev range higher you'll gain..maybe a few bhp but it will loose torque!)

remember turbo boost effects compression so after the turbo it won't affect the power

My "cough" 760 intercooler gained from a de cat made it super loud though, exhaust fitter couldnt stop giggling at me :grin:
Title: Re: de cat
Post by: AudiA8Quattro on 02 August 2009, 22:43
On a turbo car once the gas passes through the turbo it is beneficial to get rid of them as quick as poss while on a n/a car the cat will slow the gas and help compression/efficiency (and if you loose this you'll find the rev range higher you'll gain..maybe a few bhp but it will loose torque!)

remember turbo boost effects compression so after the turbo it won't affect the power

The cat actually is very restrictive on na cars.
A good example of this is the 9A engine 2.0 16v fitted to early 90's corrado and passat.
The engine was 200cc larger than the KR 1.8 16v in the golf, but actually produced 3bhp less.
The 9A engine produced much nearer to the ABF engine once de-catted and the 'soft' profile inlet cam was changed.
Title: Re: de cat
Post by: Wayne on 02 August 2009, 23:39
On a turbo car once the gas passes through the turbo it is beneficial to get rid of them as quick as poss while on a n/a car the cat will slow the gas and help compression/efficiency (and if you loose this you'll find the rev range higher you'll gain..maybe a few bhp but it will loose torque!)

remember turbo boost effects compression so after the turbo it won't affect the power

The cat actually is very restrictive on na cars.
A good example of this is the 9A engine 2.0 16v fitted to early 90's corrado and passat.
The engine was 200cc larger than the KR 1.8 16v in the golf, but actually produced 3bhp less.
The 9A engine produced much nearer to the ABF engine once de-catted and the 'soft' profile inlet cam was changed.

Fair point but newer cats are a lot better designed and the losses if any are small, I decatted my Vectra as it was knackered and gained nothing bhp wise but did feel a little bit smoother.
Title: Re: de cat
Post by: AudiA8Quattro on 03 August 2009, 10:14
I can't speak for brand new cars.
Just pointing out that a cat won't improve compression/efficiency, it is restrictive and will reduce volumetric efficiency.
Turbo cars should see better gains because the flow into the engine is higher than atmospheric pressure, so de-restricting any part of the exhaust will see a much better flow.
The principle is the same on non turbo cars, but the gain will not be quite as exaggerated.
People on the mk4 section are claiming some quite big gains from fitting a larger turbo back exhaust.
If 1.8T engines gain then non turbo engines ie. v6 should see good gains too.
Title: Re: de cat
Post by: tweed on 03 August 2009, 10:57
I've had a decat on most of my cars, also induction kits , or a good panel filter. I can honestly say the cars always seem to be a lot more responsive. I'm going to get one for my 16v if I gain 2bhp or not.
Title: Re: de cat
Post by: Mikester on 03 August 2009, 15:48
Ive always had go faster stripes on my cars, and it seems to make it faster.
Title: Re: de cat
Post by: Wayne on 03 August 2009, 16:08
Ive always had go faster stripes on my cars, and it seems to make it faster.

Shopping list on the doors is quicker.  :laugh:
Title: Re: de cat
Post by: AudiA8Quattro on 03 August 2009, 17:49
Ive always had go faster stripes on my cars, and it seems to make it faster.

Where do i get them from?  :cool:
Title: Re: de cat
Post by: Wayne on 03 August 2009, 21:40
Ive always had go faster stripes on my cars, and it seems to make it faster.

Where do i get them from?  :cool:

Halfords next to the Kenwood and Ripspeed stickers  :laugh:
Title: Re: de cat
Post by: AudiA8Quattro on 03 August 2009, 22:07
Actually i don't need go fast stickers, because my car actually is fast  :tongue:
Title: Re: de cat
Post by: VW BUSH on 04 August 2009, 01:34
Ive always had go faster stripes on my cars, and it seems to make it faster.

Lies, there not on your sig or are you saving them for the VR lump :grin: