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wrighty338

330D decat options & current MOT laws

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hi guys

im wanting to decat the 1st cat and EGR delete before remapping, im aware of the decats for 330D's but not quite sure how these will fit in with current laws regarding MOT

my understanding is we cant get away with decats / aftermarket pipes where the cats should be on diesels anymore - i last had a decat diesel golf about 4 years ago and wasnt an issue

anyone know for sure the current state with decats, im tempted between either obviously having the cat smashed out and retaining the factory pipe or the performance 1st cat pipe - im led to believe there is a secondary cat in the system but havnt looked

also is there any evidence online of performance differences between removing the standard cat and retaining the stock pipe vs a performance decat?

Thanks!

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As I understand it the 330d will be OK as long as the undertrays are in place and the secondary cats look intact. The tester doesn't remove the undertrays and consequently can't actually see the front cat (AFAIK the test on the cats is purely visual). Unless the car is an '04 or later (ie Euro4) the secondary "cats" are actually just silencers.

Edited by StuBeeDoo

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I could just make out my decat pipe when looking down in the engine bay. On the rollers i gained an extra ~10bhp after fitting the decat.

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Remember it's a visual check so if you're that worried you could always just gut it!

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I have decatted stainless down pipe then gutted secondaries. As said is just a visual plus a smoke test on diesels and mine passed fine

Sent from my iPad using Tapatalk

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It is just visual unless your car fails smoke test. They put on MOT notes that there is undertrays and engine covers in place so as to negate any fault if you have got a modification that doesn't fit with current regs.

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