Volkswagen Mark IV Forum banner

1 - 17 of 17 Posts

·
Registered
Joined
·
868 Posts
Discussion Starter · #1 ·
I have a 99 agu 1.8T and the4 flexi pipe in the downpipe is mullered. I want to put a decat on but I keep being given differnent opions and yes and no's to the idea.

Iv heard it can add anything up 16bhp but iv also heard that the ecu reads the emissions wrong which makes it slower?

Also if i do get one iv been told that a 2 piece is better than a slid pipe, is there any reasons.

Please help im desperate to sort it 2day lol
 

·
Registered
Joined
·
832 Posts
It will definatly add more BHP to your car mate but yes it can (Not saying it will) make your ECU trip out but then if you get Revo Stage II it can take into account you have not CAT and it will run fine. It will also sound a lot more growly and like it has bigger balls!

I'm getting my De-CAT this month hopefully... (Depends how quickly I can fit my new performance manifold!)

Just remember, it's not road leagl and it is morte likely to fail it's emmission's test when you take it for an MOT. Unless you know a 'friendly' garage of course [;)]

I'l let you knoe how mine gets on when I get it fitted
 

·
Registered
Joined
·
2,851 Posts
I have been runing a decat for over 2 years and have had no problems at all I have an AUM 2001 DBW 1.8T running APR software.

I have heard of the odd problem on ECU going a bit haywire but my feeling is that would be down to the lambda sensor and not the cat, on yours you should not even get a fault code coming up as the sensor is before the cat anyway unlike DBW cars where they have a sensor fore and aft of the CAT but it has not effected my performance.

2 piece I know of no company that makes such a downpipe it would not be wise IMO to create a place for the pressure to escape so close to the turbo.

Milltek and Jetex both do decats blue flame as well I think.
 

·
Registered
Joined
·
832 Posts
Did you not notice any difference in performance then? What about sound?

My mate had a 1.3 cooper mini and youcould feel the difference it made just in that!
 

·
Registered
Joined
·
878 Posts
Did you win that off ebay for £70??? If so, congrats, that was a bargain. Would be interested to hear what the quality's like.
 

·
Registered
Joined
·
2,851 Posts
Just my opinion if you want it go for it but I would steer clear as the weld on the flex looks awful and would not suprise me if it will break. secondly the connection to the second pipe which then leads to the mid silencer looks like it will blow very easily as there is no overlap and a lot of movement around that area.

Like I say it will work but I am not sure for how long buy one from blueflame or milltek and save yourself some hassle
 

·
Registered
Joined
·
2,164 Posts
What happened to the days when you used to just take your cat off the car..gut it out and put it back on ?[:p]
 

·
Registered
Joined
·
2,851 Posts
That makes no difference on the 1.8t as it is not the cat that is restrictive but the downpipe which is only 1.5 inches in diamter if that truly tiny.
 

·
Registered
Joined
·
2,164 Posts
Thats pish poor.I remember when i got my samco tip and couldnt believe how tiny the turbo inlet side was.
Put it next to an old one off my Punto Gt and that was almost twice as big.
 

·
Registered
Joined
·
2,851 Posts
but it is only a small turbo when did your punto spool up 3000 rpm ??? that K03's is spooling as low as 1500rpm.

But you are right god knows why they put suck a small outlet to reduce power is my guess and give themselves something to play with for later models?
 

·
Registered
Joined
·
806 Posts
Talking about restriction of 1.8T. The intercooler on are cars are juts ridiculous to say the least. I have seen bigger intercoolers on a 50-cc Motorbike. What where they thinking.
 

·
Registered
Joined
·
2,164 Posts
but it is only a small turbo when did your punto spool up 3000 rpm ??? that K03's is spooling as low as 1500rpm.
But you are right god knows why they put suck a small outlet to reduce power is my guess and give themselves
something to play with for later models?
Yeah, maybe around 2.5k.Then all hell broke loose.Such a hilarious car to drive.Running up to 1.7bar
overboost as standard and weighing less than a tonne you can imagine the fun i had in it [:D]
 

·
Registered
Joined
·
2,851 Posts
waynepixel - true they are small but they work for the job required when you up the boost they are fine for anything but high rpm continous driving such as top speed runs.

Even on hot days after a good rag my used to be fine.

Mo - I bet what where they 1.3's or something 130bhp standard typical old turbo rules got them cheap because nobody wants them put them on that engine and make it work ish. far to big a turbo for such a small engine. but fun none the less
 

·
Registered
Joined
·
2,164 Posts
Mo - I bet what where they 1.3's or something 130bhp standard typical old turbo rules got them cheap because
nobody wants them put them on that engine and make it work ish. far to big a turbo for such a small engine. but fun none the less
Yeah 1.4 136hp (ihi Turbo) but most of these were in fact around 155hp 0-60 was supposed to be 8sec but was more like 7.5-7.9.
Remembering that this car came out like 12 years ago it was very quick in comparison to what was around at the time.Increase the
boost a touch and your looking at around 6.9-7 seconds to 60. [Y][;)]
 

·
Registered
Joined
·
553 Posts
Hi mate

I would air on the side of caution & fit a full SS sytem inc sport cat. I decided that this was the more real world option and got the

full miltek fitted. inc sport cat. It just been MOT and no emisions problems like you would have with a decat,

the car sounds sweet, the turbo pick up quicker and the no problems with the ECU.

just my opinion, good luck

Rb
 
1 - 17 of 17 Posts
Top