i already have a TSL centre and back box on my MY01 -what gives most performance gain-a de-cat uppipe-or a de-cat downpipe-i only want one or the other as when it comes to MOT time i will have to just stick centre cat back on and it will pass emissions-so ur views please-and not wanting to re-map my ECU-maybe in future tho but i want long term reliabilty as well

 

Most gains and better throttle response is from downpipe and is easier to change this when comes MOT time rather up pipe.
Of course if your car is >MY01 you should also change up pipe as it's common to split when the rest is full decat in order to protect your turbo!
JIM

 

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If you do a search, you will find that it is recomended to replace the up and downpipe at the same time(partly being that you have to remove the d.pipe to get to the u.pipe),and then all you will have to do is refit your centre section cat for mot time.

 

will it get thro mot will just a centre cat on tho??

 

It's well worth doing the upipe& downpipe at the same time on the My01.

If you leave the centre cat in & the car is running hot then yes it will get through an MOT.......

 

r u sure it will get thro an MOT-as if it needed a second cat putting back on im guessing that be a long and expensive job just for a MOT- as its due its first one in september -how much am i looking at to get an uppipe and downpipe done and where do u recommend-im in staffordshire