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Wrx 03 exhaust help

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Hi guys, looking for some advice on what to get/do. Currently have a prodrive backbox and (i think) centre section that i bought off the 'bay. The centre section has rusty flanges despite being a stainless pipe (not a fan of dirty flanges) and doesn't seal very well at the bb flange so I'm considering replacing the centre section and 2nd cat with a decat and keeping the back box. The questions are:

Do prodrive centre sections have cast flanges as opposed to stainless or have i been stitched up?

Will a 2nd decat throw a CEL or require a remap?

What is the standard downpipe cat capable of flowing power-wise? As tempting as it is, i want to try keep it emissions test friendly rather than going down the full decat route.

Sorry for the amateur questions, i have done a search but couldn't find what i was looking for!

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You can normally get rid of the Up pipe cat with no MOT Issues, aftermarket sports cats remember you need them hot for them to work well and pass the MOT, 


if you were to do any i would say the Up-Pipe (get a decat one from the STI), its a bigger job to get it fitted as it means taking out the turbo (Probably £160 fitting cost) but will give good response different, also it can be an issue if they disintegrate the cat inside goes through your turbo and ruins it. 

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if it was me I would re-map. one to get the most out of your better breathing and two to stop any over boosting or anything like that :) 


but if you are getting the re-map it may be best to think what else you may do in the future and trying to combine it all together to save re-re-mapping down the line. 

(trust me, Mines in for its third re-map :')  )

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Yes you will need a map ideally as the turbo will possibly be over spooling due to the gasses flowing quicker

Plus you'll end up with eml codes being thrown up which won't be able to remove without mapping

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