Page 1 of 1
De-cat pipe
Posted: Mon Dec 17, 2007 10:36 am
by CraigMK4
Have been considering this mod lately, but what are the main advantages and disadvantages? I heard it can increase power (or get back whats restricted from the cat) and can also improve the sound. My friend seems to think it could cause problems with the lambda sensor though? Also, where can i buy one from? Thanks a lot guys!
Re: De-cat pipe
Posted: Mon Dec 17, 2007 12:44 pm
by bstardchild
CraigMK4 wrote:Have been considering this mod lately, but what are the main advantages and disadvantages? I heard it can increase power (or get back whats restricted from the cat) and can also improve the sound. My friend seems to think it could cause problems with the lambda sensor though? Also, where can i buy one from? Thanks a lot guys!
Did this a long while back (there are definately some pictures on here) - unfortunately for me it wasn't an off the shelf item - I had to cut the cat out, flange it and flange the downpipes so I could make a bolt in bolt out section so I could put the cat back in every year for the MOT
Advantages
- No smelly cat
- Better mpg (probably about 1 - 2 mpg better)
- Bit more mid range (or more of a flat spot that the AEX engines have - very throttle dependant)
Disadvantages
- Bit of a faff to convert a downpipe to be cat free in a way that still allowed a cat to be inserted for the anual MOT
- Exhaust has a slightly raspy tone (not bad just slightly raspy)
Thats about it really - It (the car and the ECU) don't know the cat has been removed as the lambda is fitted before the cat and unlike my 7 series it doesn't have another lambda after the cat to monitor how well it's working!
I dislike cats so I'm working on a way of ridding my 7 of them - it's just a different approach
Edited to add
Original post when I did it (pics may or may not still work let me know if they don't - I can't tell from where I am now)
http://www.tigerstyle.co.uk/poloforum/v ... 85&start=0
Posted: Mon Dec 17, 2007 1:15 pm
by JarnoVWPolo6N
Advantages:
-more power (on average, a catalyc "stops" about 8% of an engines power, ON AVERAGE!)
-more sound, since the cat dempens the engine-noise
And no, you won't come into trouble with the lambda sensor, since it's mounted in front of the cat, not inside it, so it can be removed, I replaced mine with a sports-cat, is like a freeflow muffler, so no air-restriction and not to much extra sound, more of a grunt
Posted: Mon Dec 17, 2007 1:59 pm
by NOZ
I thought MPG worsens!!!
My mates polo had a de-cat, I could smell the fumes coming outta it when driving behind him!!!
Posted: Mon Dec 17, 2007 3:12 pm
by bstardchild
NOZ wrote:I thought MPG worsens!!!
My mates polo had a de-cat, I could smell the fumes coming outta it when driving behind him!!!
Mpg improves - cat = restriction
If your mate de-catted and you could smell fumes then something else was wrong