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The mkiv Supra Owners Club

CW de-cat on a UK spec auto with stock exhaust


carl0s

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I like my stock exhaust. I sounds nice, but I want it a little bit more aggressive sometimes, not bad-boy though.

 

I also want more power.

 

It has been suggested that de-catting will have no benefit with a stock exhaust. Is this a defo?

 

Surely there will still be gains?

 

Chris?

 

Would it be a bastard for me to fit the de-cat pipe myself, being a cheapskate? I'd probably only do the number-1 CAT to begin with.

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The first cat (the one nearest the engine) would be difficult to do yourself. It's not easy to get at and the manifold nuts get really rusty because they are exposed to a lot of heat. I guess that's why a lot of folks do the second cat first.

I'm sure you'd see a nice boost in performance even with the standard exhaust..

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Would it be a bastard for me to fit the de-cat pipe myself, being a cheapskate? I'd probably only do the number-1 CAT to begin with

 

Definately!

 

The first cat can be a pain!

 

Not easy to get to the nuts, you have to use a long extension with the wrench.

 

I replaced both cats myself last week, 2 nuts were tight but came loose okay.

 

The third one was a right b**tard, the socket rounded off the corners and I had to go out and buy a nut splitter then bash on another socket to remove it.

 

Normally a damaged nut isn't a problem but it is in such an awkward place.

 

On the older cars when undoing the nuts you run the risk of shearing off the studs, you would then have to remove the turbo elbow!

 

If eveything comes loose okay then it is an easy job but if you run into problems you'll wish you paid someone else to do it!

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I don't think you would see/feel much, if any, gain really. IMO

 

I pulled both cats and fitted CW's decats and a Hiper and moved from 0.8 bar to 0.9 bar on my UK Auto. The car felt much better then :D

 

You could always move to a quiet type exhaust, stock sounding ish but, a little bit more Grr and loose a cat ?

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Originally posted by Barney

Always wise, before you start, to get a set of new studs if you are going to tackle taking out the first cat.

 

I now find more snap than come out clean and thats even when using the Hot Spanner on them , they allways crack off fine but 'freeze' a short way down the thread !!!!!!

 

Dude:flame Dev

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Originally posted by dude

I now find more snap than come out clean and thats even when using the Hot Spanner on them , they allways crack off fine but 'freeze' a short way down the thread !!!!!!

 

Dude:flame Dev

 

Too true Dude! The ones that look brand new and factory fresh often seize, yet the mankiest ones often undo with no problem. I now keep the correct helicoil kit and inserts to hand with new studs and nuts, and a proper stud extractor. Even with all the right gear they can be a Royal PITA.

 

BTW Dude, who makes GOOD double sided tape for fitting body kits? I took a side sill extension off my car to have a look underneath and now want to re attach it. My local factors only sell Pearl brand generic double sided tape, and it's not very thick, nor very sticky. I suspect I should get something better, 3M maybe? Cheers Dude!

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Chris,

Are helicoils really necessary? If space allows, I've always drilled out snapped exhaust manifold studs and retapped them with the next size up (coarse) thread. It's no picnic but it's a lot easier than helicoils :shudder:

 

 

 

 

 

 

 

DISCLAIMER:

I'm aware that the aforementioned CW method is undoubtably the more professional method

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okie dokie. I really wish there was a resource of mp3's or .wav's of different exhausts on MK4's.

 

On the one hand I love the sound of a Diablo, and I love the helicopter like hum of an idling Ferrari 575, but on the other I want to remain slightly conspicuous most of the time.

 

Do the words subtle and Supra have any kind of meeting, anywhere?

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Originally posted by Jake

Chris,

Are helicoils really necessary? If space allows, I've always drilled out snapped exhaust manifold studs and retapped them with the next size up (coarse) thread. It's no picnic but it's a lot easier than helicoils :shudder:

 

Can't see why that is easier than helicoiling back to a stock size stud? A properly inserted helicoil is stronger than a basic thread in the parent meta. Rolls Royce used to helicoil every important thread in alloy castings, just to give a thread that could take more torque. Helicoils are really easy to use, unlike the (better) Keen Serts.

 

 

 

 

DISCLAIMER:

I'm aware that the aforementioned CW method is undoubtably the more professional method

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