myk3

Hi all,

Please can anyone recommend a full turbo back decat 3" system for my 04 STI?

Also is it possible to change out the cat section of the system come MOT with the stock pipe or will the 3" be to big for the stock pipes/flanges? or will I have to replace the whole system from the turbo with the stock one for MOT only? I am happy to do this once a year myself if needed.

ideally i was hoping that there is a De-cat system which you can quickly change out one of the sections for cat? If anyone can advise on this or something you have put in place to make this possible that would be great.

Before anyone says, i dont want to go down the sports cat route, im hoping to go down the SC46 turbo route in the future and want the best possible spool/performance from it.

Thanks,

Mike

Rbon91

iTrader: (6)

If your lucky mate just put standard cat in for not should be fine as long as its not a custom exhaust system should fit. Or am sure you can find somewhere who will give you a mot without having to change over exhaust. For few quid

Jacko4130

iTrader: (3)

Costs £20 round my end to get round that problem

myk3

thanks for the replies. I am hoping that i can find a "friendly" place the are de-cat friendly . But i cant count on this and like i said id be happy to swap out for the cat once a year.

What I was hoping is that someone could tell me that i could keep the cat section of the stock exhaust system and each year swap only that part out and if this will fit an after market 3" turbo back system like Milltek for e.g.?

The alternative to this would get to get a fabby to weld a vband straight through pipe and also a cat using vband flanges which will take literately 2 mins to swap out the cat. This is what i did on my 1.8T Golf back in the day.

cheers,

mike

TonyBurns

iTrader: (3)

You cant do it, you have to go sports cat, and before you say you dont want it because you will lose spool, total bs you wont even notice with a sports cat, it flows as good as a decat pipe but keeps your emissions down.
Also, you cannot just change back to a cat from a decat as your car will be mapped for one but not the other, it can cause issues, even put your emissons out with the cat on, so the safest way is sports cat.

Tony

myk3

Thanks for your reply Tony. Your reply makes sense.

funny really the 1.8T VAG engines run fine with and without the CAT when i had it set-up with the swap out option. I'm assuming the Subaru ECUs are less adaptive and thus a remap is required for such modifications?