the garage i bought my 91 300zx twin turbo manual jspec from has said they can remove the cats from my car for £200 and say it will give me a 40bhp increase and also said it would have no problems passing a mot without the cats does this sound right i would hate to get them removed only to find out i have to buy new ones come mot time and if this is correct thats a lot of horses for 200 bucks

 

thanks

 

Paul

 

 

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well first of the 40 bhp is a load of KAK full stop.

it wont give you an extra 40 brake, it will certainly help in torque and spool up and make more power at lower rpm and is better to have no cats for turbos want as little restriction as possible.

200 squid to do that job is very expensive. are they going to use a complete replacment exhaust section for that ? if not it should cost no more than 50 squid to make up replacment pipes.

Johnny at GPS sells de-cat pipes for about the same price. It is impossibe to say how much bhp will give you, every engine is different and it depends on how much the engine is modified.

By the sound of it they garage will just drill out the cat from the downpipes where Johnny you will get new pipes.

You will find that the turbos spin up quicker and you will feel more power. As for the 40bhp, I dont know if that is true but it is a noticable amount.

One downside to de-cat pipes is the back pressure on the turbos is greatly increased, which could cause the turbo seals to leak creating great puffs of blue smoke from the exhaust. If your turbo seals are upto it you will be fine. If they are getting on a little, they would last as long as they should with de-cat pipes. Its fine cos its only £20 or so for the seals, but cost you a few hundred to have them put on becuase you are virtually doing all the work for a turbo change.

 

As for the MOT, you are legaly allowed to take them off on a H reg, but a few people on here have had trouble passing the emmisions on the MOT with them on and with no cats the gases increase, but it is possible to pass with them off.

 

One more thing, the noise of the car is louder, whether this is a plus or a minus for doing it is down to personal choice.

 

Stuart

ok thanks guys the garage said they would just be removing the cats with no replacement pipes but on the upside they are going to replace the turbo seals at the same time the car is going in for:

a competion clutch

a super lightweight flywheel

a twin induction kit

a set of irridium plugs

the cats removed

and to have a greddy turbo timer fitted and an apexi boost gauge

so im hoping the car will feel a lot quicker when i pick it up

Beware the lightweight Flywheel - if you don't want to do away with that nice smooth driveability that the Z has.

Semco, what garage are you using??? From a few of the points you have mentioned they seem pretty clueless about what they are doing. £200 to remove the material from inside the cats??? put that another way - £200 for 20 mins work....

the £200 is for removing the cats and replacing the turbo seals at the same time

the full price list is:

timing belt change and fit lightend under drive pulley set and fit plugs=£200

fit clutch and flywheel=£120

fitting induction kit=£75

fitting turbo timer and boost gauge=£50

i know they are dear for some of the things but all in they seem to be the cheapest in my area which is edinburgh

It's correct that your 1991 car will pass an mot without cats. I'm in the same situation, had no cats for 3 mots now.

 

[This message has been edited by Jez (edited 17-09-2002).]

I was looking at getting some cat replacement pipes with small silencers from zcentre. They are £260 from the zcentre. Anyone know how good these are and if this is a good price?

does anyone bother gutting the pre-cats??

 

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I feel the need, the need for speed!

 

Originally posted by Jez:

It's correct that your 1991 car will pass an mot without cats. I'm in the same situation, had no cats for 3 mots now.

 

[This message has been edited by Jez (edited 17-09-2002).]

 

It is LEGAL to take off cats from a car if it was on the original spec if the car is pre K reg.

If the orginal spec of the car had cats and is K reg or younger it is ILLEGAL to remove them regardless the emmissions.

 

So you cann't be charged for having no cats on your H reg. You can be charged for no cats on a K reg or younger.

 

De-catting doesnt help the emissions but most people still pass even with them off.

 

Stuart

 

Stuart

When you say turbo seals, they can't be talking about the actual rear seals on the turbo - they must be talking about exhaust gaskets. No way could they fit new rear seals to 2 turbos AND gut your cats for £200

 

Hint hint - GPS do decat pipes at a very reasonable price 01942671239

 

HTH

 

CheerZ,

 

Andy

Originally posted by andyduff:

When you say turbo seals, they can't be talking about the actual rear seals on the turbo - they must be talking about exhaust gaskets. No way could they fit new rear seals to 2 turbos AND gut your cats for £200

 

Hint hint - GPS do decat pipes at a very reasonable price 01942671239

 

HTH

 

CheerZ,

 

Andy

 

exactly what i thought, they would have to remove the turbos altogether and that costs a lot of time and money...i know i have had it done.

 

steve

 

 

i will ask them again which seals they mean when they say turbo seals

Stuart I have a 1994 twin turbo which i decatted 2years ago I had my last m.o.t done at a nissan dealer which it passed and today I had it done at a local garage and they passed it too,when I asked about the years he showed me the m.o.t manual which states cats must be fitted to all cars after 31st july 1994,Ive had a 300 tt for over 5years now and I had always been told it was 1993 K

but i guess i was wrong.

 

Cheerz Terry

 

Hmmm thats interesting, cos I found a government site that said 92 and there was a poster in the MOT centre wall saying 92.

 

Have to look into it.

 

But the fact is, there is no way they can know that its decatted is if they take the pipes off and have a look and whos gonna do that?

 

Stuart

Mine absolutely flies through the emissions miles under the limit with no cats so I think they dont do much anyway. Anyway surely you guys must have a mate or know the local garage owner who wont give a s**t if you have no cats, your not takin your car to somewhere snooty like Halfords are you

Paul

 

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all passenger cars fist used on or after 1 august 92 are subject to cat test *unless* :

 

no exact match in gas analyzer database

 

or vehicle used between 1 august 92 - 31 july 94 which is a NON PASSENGER CAR

 

physically not having cats fitted is NOT reason for rejection.

 

 

 

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I feel the need, the need for speed!