Results 1 to 7 of 7
  1. #1
    Forum User Standaman94's Avatar
    Join Date
    Jan 2015
    Location
    Colchester, Essex
    Posts
    164

    Question To Cat or not to Cat

    My Williams failed it's MOT on emissions because, unbeknownst to be, it was fitted with a decat pipe (it all makes sense now!)

    So the garage is getting a Cat and putting it on to pass the MOT.

    The question is, however, after the MOT do I put the decat back on or not? I know it will sound "better" but I'm more interested in power and fuel usage.

  2. #2
    Subscribed Member
    Join Date
    Sep 2008
    Location
    LUTON
    Posts
    962
    If your not bothered leave it on mate saves swapping it over every year

  3. #3
    Or find a more friendly MOT tester & leave it de-catted

  4. #4
    Forum User Standaman94's Avatar
    Join Date
    Jan 2015
    Location
    Colchester, Essex
    Posts
    164
    What about fuel efficiency... Does a decat use more or less fuel?

  5. #5
    Fuel use is entirely dependant on how heavy your right foot is, the lambda sensor is before the cat so it wont make any difference if it's got a cat or not, removing the cat gets rid of a restriction making the gases flow more efficiently

  6. #6
    Forum User
    Join Date
    Jun 2013
    Location
    Warsaw, PL
    Posts
    101
    Bumpitty. Any issues with fitting a decat? Will the car need any mapping after or is it a "good to go" job?

    Sent from my SM-A300FU using Tapatalk

  7. #7
    Technically mapping it would be best but the cost would be extreme for little or no difference, the actual benefits would be negligible. It's basically good to go. The restriction from a cat is unnecessary and I would always remove even if that means taking it in and out for tests.


 

Similar Threads

  1. Cat just gone any advice? Sports Cat? Best you can buy?
    By jjustice in forum WilliamsClio Discussion
    Replies: 17
    Last Post: 21-12-2010, 16:02
  2. Replies: 3
    Last Post: 25-02-2008, 20:02
  3. valver manifold or willy one? beaten cat or de-cat?
    By midge in forum Performance/ECU Tuning
    Replies: 5
    Last Post: 02-10-2007, 12:36
  4. Williams Cat or Sports Cat
    By drsmith1979 in forum Wanted
    Replies: 3
    Last Post: 02-07-2007, 19:26
  5. Williams stainless cat-back system and de-cat
    By Zollo in forum Items for Sale
    Replies: 18
    Last Post: 23-04-2007, 08:47

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •