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The mkiv Supra Owners Club

Full decat or not?


Geezabloke
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Should i go for full decat.............or keep one cat and fit a boost controller, cold plugs and fuel cut chip?

Which would be the most reliable and most beneficial in raising the low down pull on a UK TT?

Just need some guidance as a bit new to it all..........

Dave :D

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I'm assuming you've spent ages using the search button for the pros and cons of De-catting a UK Supra...as it has been covered once or twice....:innocent:

 

well if re-fitting it for the MOT is too big a problem then fair enough, otherwise there is no reason not to de-cat a UK car...

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One thing....

 

I used a ONE-piece down-pipe, replacing both cats with a SINGLE

pipe.

 

That looks lovely / less bolts etc. = great.

 

HOWEVER, I can't put ONE cat back in (IF I wanted/needed to!?)

 

I should have (may STILL) get a TWO-piece down-pipe so that I

can put just the lower/second cat in (easier than top cat and

EITHER will pass MOT easily).

 

Just a minor point, but..................

 

BUT............. BOTH CAT'S OUT ! ! ! ! !

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Originally posted by Steve W

I used a ONE-piece down-pipe, replacing both cats with a SINGLE pipe.

HOWEVER, I can't put ONE cat back in (IF I wanted/needed to!?)

Is the one piece decat downpipe harder to fit than the usuall two stage job then? I mean, you'll be swapping straight back to no cats after the MoT test anyways, right?

 

Oh, and where can these de-cat conversion pipes be purchased?

How long do they take to install? (assuming not a complete muppet)

Any special tools req'd to fit?

 

--

Dunk 657

'93 J-Spec TT, Auto, Std Mechanically, Bomex Kit

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Putting the 1-Piece on is exactly the same as putting a 2-Piece

on......(well, 2 bolts less, but doesn't really matter)

 

BUT, it's when it comes to putting ONE cat back in....

 

I would have to put BOTH back....that means getting up to the

Turbo end bit:mad:

 

If you have the 2-Piece pipe, you can just put the second/lower

cat' back in which means just the 'easier' joins UNDER the car.

 

No big AG' for once-a-year, just a thought when you're buying

it mate....? ! ? !

 

( I DON'T need to put the cat' back in.... while I'm going to my

usual MOT station:p but if I get an UNfriendly one it's a

tad more AG' with my 1-Piece.......mak sense?:conf: )

 

FatS.

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Originally posted by Andrew

Still deciding this one for myself too.

 

Some great posts if you look in search.

 

Personally I'm a bit of a sound freak, common sense says leave cat1 in, my heart wants full decat ;)

 

You've got a J-spec there are other things to consider.

 

UK's don't overboost so the only issue is swapping pipes at the MOT.

 

 

Geeza,

Just get 2x CW de-cat pipes and a catback exhaust. Its tried and tested - works fine.

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DON'T DO IT. My experience of a full de-cat was an out of control boost and a big wheel-spin problem. On my J-spec car it made the power delivery too severe for everyday driving. My personal opinion only here, is that a boost controller is the only way to go. I get the same power as a decat car but it's controlable and you can dial it down when the roads are wet or the air temperature is low.

 

My verdict - highly over-rated.

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This thread is about a

 

UK CAR!!!!!!!

 

Not a J-spec....

 

FFS can anyone read anymore???

 

benefits on a UK car =

Less Lag

Lower EGT's - even with the higher boost

More boost - About 1.1-1.2bar

 

detractors =

Have to re-fit at least 1 cat for an MOT

Fuel consumption increases :D

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Good thread, one of many on the subject...

 

I have left mine in due to conversation surrounding piston concerns after a while if they are both removed > I must find out why.. perhaps due to over boosting?

 

Chris Wilson sells the decat pipes, I may purchase. In the mean time I have a GREDDY fuel cut defencer which is brand-new but is not programmable and therefore for those with electronic boosters in mind > aka another £1400! I'll take £75, was £95 new.

 

In the mean time if anyone can tell me where, and how much the programmable defencer is which cut's 19 PSI (what is that?> 1.2 bar) I would be very grateful. Remember seeing it discussed in a thread.

 

With one CAT removed and running a hyper Muff, I hit 1 bar and fuel cut. :)

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Originally posted by John Packham

Is the UK car THAT different to the J-spec?

 

yes :)

 

I believe its all in the wastegate and exhaust sizing/construction....sorry about earlier, got out of the wrong side of the bed, and the wall was none too forgiving... :music:

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Until recently i was under the impression that i had a straight through exhaust. Took the car for an MOT and had Leon put the rear silencer on it beforehand. Only while we were under the ramp did he notice that the front silencer pipe was in place but the internals had been removed giving no cats without the proper pipe.

 

This is either ingenious as you have effectively a straight through exhaust allowing easy connection of the rear cat once a year (passed MOT fine) or a total bodge.

 

Any opinions??

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Alex - No worries mate.

 

I realised I'd posted J-spec info against a tech query on UK, but this whole decat business gets to me. My car was undriveable with both cats out, the second turbo came in at 1.1bar like a light switch and I spent most of my driving lifting off at 4000 just to keep traction. Being an auto, it changed up as soon as I lifted. I've put the second cat back in and it's fine.

 

Anybody want to buy a CW 2nd decat pipe?

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Originally posted by John Packham

Alex - No worries mate.

 

I realised I'd posted J-spec info against a tech query on UK, but this whole decat business gets to me. My car was undriveable with both cats out, the second turbo came in at 1.1bar like a light switch and I spent most of my driving lifting off at 4000 just to keep traction. Being an auto, it changed up as soon as I lifted. I've put the second cat back in and it's fine.

 

Anybody want to buy a CW 2nd decat pipe?

 

Can't see why you were having that much trouble if you were only hitting 1.1bar (I hit 1.45 before restrictor plate). And surely if using manual mode your gearbox wouldn't change up?

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