I have an import WRX with the origonal Jap aftermarket non stainless system on it. Thinking of changing it. How does the de cat thing work?

Obviously a new system has no cats. What happens for the MOT? How easy is it for people to take cats in and out and do peolple just take them in and out of the center section and leave the down pipe with out a cat.

Any advice appreciated
Best wishes
Steve

 

As for the effect, you're letting your turbo spin easier as the exhaust gas is unrestricted. The first time you try to unbolt the downpipe from the turbo is going to be the most difficult bit (like plucking a virgin) as Subaru Japan has this horrible habbit of overtightening thing and that and that the nuts might have heat fitted itself to the studs. The bolts might have seized in. If its been changed before, its easy and takes only 10 minutes to change. You'll need to do it for the MOT. Hope this helps.

 

Steve
I would hook deltadsh on your car before and after the decat to see of any lean spots in your fueling. Many UK and JDM cars have blown up due to de-cats. It can play with your boost levels and fueling in a weird way so watch out. To get the full advantakes its a good idea to get your std ecu upgraded to a tek 3.

Gez

 

Thanks for the advice. Really appreciated.
Have just found out that there is only one cat which is the front one. (I am sure I have heard of people replacing one in the center, I suppose due to easier access. Perhaps this is just my imagination.)
Also mating a stainless item to a non stainless item seems to be no problem

Steve

 

All UK cars have centre cats as standard as well as the main downpipe one. Many Jap imports (like my MY98 WRX and I would guess all STI's) do without this centre cat as standard but will still pass the MOT no problem.

 

Steve,
My car has no cats in it, and it's passed the MOT with no problems. Talk to Graham at GDA and ask him about decatted systems.

 

I believe any import older than 1995 doesn't need a cat. (UK cars need a cat if MY93 or newer). Unfortunately mines a MY95 WRX so needs a cat to pass the MOT! Have just had it done so over for another year!

 

ZAZ that is very interesting. So If my car is a MY94 WRX I can remove the front cat and it can have an MOT with out the cat. Can you confirm this?

So Markus. Therefore as your car in a MY94 WRX do you permantly leave the CAT out and does this get through its MOT like this. Or is the cat put back in?

So hopefuly I just need to remove the front CAT and forget about it.Thanks for your help
Steve

 

This is what I was told by GDA. http://www.gdasportscars.co.uk/
I left the car with them to get it MOTed (as I can't be bothered to swap the cat myself) and they rang the MOT centre to confirm that it needed the cat and that was what they were told!

 

Am going to see Graham on the 6th. So will chat to him about it then.
Best wishes
Steve

 

Steve,
Can confirm that my car, with NO cats (BPM Twindump Downpipe, and Apexi N1 center/backbox) passed it's mot with no problems at all. I've now got a Blitz Nur Spec R on it, and I've no doubt that this will pass as well.

I might see you down GDA on the 6th, as I need to sort the PAS out.

 

Thanks Markus
Have a good christmas
Best wishes
Steve

 

I've seen this debate before and I think the result was that no car originally manufactured with a CAT will pass a UK MOT legally without one, import or not. If there is a year when this became the rule then I believe it was before the Impreza was released. I guess it may depend on the MOT tester though and their interpretation of the rules on imports...