Page 1 of 2 12 LastLast
Results 1 to 10 of 11

Thread: Is a de cat really needed?

  
  1. #1
    Status
    Offline
    buzball's Avatar
    Supporting Trader
    Join Date
    Nov 2009
    Posts
    2,376
    Mentioned in
    0 Post(s)
    Quoted
    0 Post(s)

    Is a de cat really needed?

    Hello guys im getting a full exhaust system 2.5inch from the 1st cat under the manifold all the way back

    Do i really need to get a 1st de cat as there not exactly cheap lol

    Im aiming for around 280-300bhp in the future

  2. #2
    Status
    Offline
    GB's Avatar
    AOC Obsessed
    Join Date
    Jan 2006
    Location
    Leeds
    Posts
    21,918
    Mentioned in
    0 Post(s)
    Quoted
    0 Post(s)
    £100 or thereabouts will get u a decat precat so not really mind blowingly expensive!

    "from the 1st cat under the manifold" u say --- surely that includes the precat???

    its the main cat under the engine bay which is the expensive one ~ £350+

    Precat decat is the first mod any ZLEx owner should carry out imo


    just remember that most coupes (for the coupe owners out there) have a precat and main cat all in one assembly so either need to find a main cat of a gsi/sri-t for example or buy a brand new sports main cat

  3. #3
    Status
    Offline
    buzball's Avatar
    Supporting Trader
    Join Date
    Nov 2009
    Posts
    2,376
    Mentioned in
    0 Post(s)
    Quoted
    0 Post(s)
    Yeh true not to bad then, maybe im getting a little confused

    Im getting a system from the flange just under cat manifold back

    So basically it will go turbo cat then all the way back 2.5inch

    But if i get that decat it will be turbo decat then 2.5 all way back

    Does that sound right sorry for the confusing

  4. #4
    Status
    Offline
    GB's Avatar
    AOC Obsessed
    Join Date
    Jan 2006
    Location
    Leeds
    Posts
    21,918
    Mentioned in
    0 Post(s)
    Quoted
    0 Post(s)
    the cat (precat) that attaches onto the turbo is what cost about £110 delivered and this is an essential mod in most turbo owners minds

    the next section is the main cat assembly which runs from the precat flange (3 bolts) to the start of the centre section (2 bolt flange) **This is the expensive part**
    BUT I would advise you go "sports cat" here and not a decat!!!

    Sports cat will cost about £350+ or just re-use your original main cat assembly for now (presuming u aint got a coupe!)

    next is the centre section then the rear section

    4 parts in total

    a "turbo back" system generally comprises all 4 components but features a sports cat (advisable) or a decat (not ideal - will probs fail MOT if not bodged and defo fail roadside emissions VOSA tests)

    If u want to retain ur standard main cat assembly to keep costs down then just get a cat back system (centre and rear box) and then an off the shelf precat decat - so ur essentially retaining ur main cat but replacing the other 3 parts

  5. #5
    Status
    Offline
    buzball's Avatar
    Supporting Trader
    Join Date
    Nov 2009
    Posts
    2,376
    Mentioned in
    0 Post(s)
    Quoted
    0 Post(s)
    Thanks for the good advice there mate ive already brought a system to bolt on to the pre cat system

    I know about mot etc but the system im getting dont have a cat

    Will the car run ok?

    P.s ive already got a cat back system but its only 2inch and thought that would be to small for the power i want?????

  6. #6
    Status
    Offline
    GB's Avatar
    AOC Obsessed
    Join Date
    Jan 2006
    Location
    Leeds
    Posts
    21,918
    Mentioned in
    0 Post(s)
    Quoted
    0 Post(s)
    have u got a link to the system youve got?

    so are u saying youve boght a "decat" ?? id have opted for sports cat personally but each to their own

    may as well chuck on a decat precat whilst ur replacing that lot

    post the link anyway if u can and we can let u know

  7. #7
    Status
    Offline
    buzball's Avatar
    Supporting Trader
    Join Date
    Nov 2009
    Posts
    2,376
    Mentioned in
    0 Post(s)
    Quoted
    0 Post(s)
    No link mate its a poweflow system from a mk4 astra but with a c20let so was going to cut a little from the end change the flange etc

    I would rather keep with my system to be honest ive got but 2inch i think is to small?

    P.s i had to choice of having a cat its 2nd hand

  8. #8
    Status
    Offline
    GB's Avatar
    AOC Obsessed
    Join Date
    Jan 2006
    Location
    Leeds
    Posts
    21,918
    Mentioned in
    0 Post(s)
    Quoted
    0 Post(s)
    sorry but the way this thread was worded didnt sound like youd already bought a decat system - sounded more like u were considering one!

    if its standard ZLET then youll have 2.25"

    if the main cat on the one youve got is a decat or just a straight through pipe then you may need a threaded boss welded in and the lambda (rear one) spaced out a little so it dont read the emissions fully - this may prevent the EML coming on but would still more than likely fail emissions testing but u know that

    time will tell what the system is like though cos im confuddled now lol

  9. #9
    Status
    Offline
    buzball's Avatar
    Supporting Trader
    Join Date
    Nov 2009
    Posts
    2,376
    Mentioned in
    0 Post(s)
    Quoted
    0 Post(s)
    Il try and do my best to explain mate

    At the moment ive got a long life cat back system I think it 2 or 2.25inch

    Ive now brought a full powerflow system from a mk4 astra c20let, will adapte to fit. thats 2.5inch

    Im really confused maybe i should keep my system and get a precat?

    And sell the one ive just brought??

    Thanks for all your help mate cheers

  10. #10
    Status
    Offline
    GB's Avatar
    AOC Obsessed
    Join Date
    Jan 2006
    Location
    Leeds
    Posts
    21,918
    Mentioned in
    0 Post(s)
    Quoted
    0 Post(s)
    well 2.5" will certainly be better - if its from a mk4 clet then the lambda boss would have already been fitted for the mk4 it came from so should be a straight fit - once youve modded the precat to fit

    should be ok personally - but u may wanna get an off the shelf 200cpi cat and have it welded into the powerflow one youve bought - only cost about £120 or so and will keep everything official and legal whilst still gaining performance

    and of course the precat


    obviously u could just whack on the powerflow as is once youve modded the precat end etc but ur always gonna be running the risk of "what if" when using a decat

    thats just my take on it though - see what its like when it arrives and how much work is involved making it fit etc - and having a cat fitted

Page 1 of 2 12 LastLast

Similar Threads

  1. help needed with bodykit (photoshop needed)
    By pog in forum Bodywork and Exterior
    Replies: 3
    Last Post: 25-02-2009, 19:05
  2. Tools needed to lower front of my cab - help needed
    By paulocardyo in forum Astra Discussion & Chat
    Replies: 6
    Last Post: 04-06-2008, 20:49
  3. New Laptop needed, spec advise needed please
    By Sausages in forum Chit Chat and a Warm Welcome!
    Replies: 23
    Last Post: 22-01-2008, 10:21

Posting Permissions

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