Hi all,
I’m looking at having some pops and crackle on my mk4. I am installing the cobalt rear silencer over the next few weeks or so. Cobra do a straight pipe so hoping both will help. Just wondering how many cats the car has as legally you need to have at least 1.
Ta
It has 2, 1 in the manifold and 1 before the resonator
Wouldn’t that mean that it needs both of them to keep the emissions to a legal level?
No the cat in the manifold is designed to work pretty quickly from cold but after that its the cat before the resonator that does the work. Academic if you are going to change to a catback system
So so it’s probably better to replace the manifold with one without the cat instead of removing the cat in front of the resonator?
the mid pipe I was looking at getting was:
You need a non-resonated cat back pipe.
so the one from cobra I posted above is no good?
The Oxy sensors are before and after the first cat, therefore the exhaust emmissions have to be within paramaters before the second cat which will complete the job.
For an MOT, the car can fail if the original items are removed, this assumes the “Tester” knows how many cats are on that specific car which is a long shot.
Therefore you need both units and also to have a system that brings the car within the emmission range for the that car to stop you breaking the law and to be sure of getting an MOT pass.
In that case, what options do I have?
To physically phone suppliers and going over in detail with them what system is legal and will pass an MOT.
You also need to cut the resonator off the rear of your existing centre section and then add the new part of the mid pipe that the aftermarket exhaust manufacturer supply to the existing second cat.
We are talking here about you having a legal car and it is not up to the MOT tester to find a way for a punter to have an aftermarket exhaust. It is up to you to have a car that abides by MOT regulations and type approvals not the other way round.
This is what the MOT testers manual states re a major fault.
Defect Category
Emission control equipment fitted by the manufacturer: missing, obviously modified or obviously defective
MajorAs Eddie says, the new MOT rules are clear. Cars should have their original cats, DPFs, etc in place on the exhaust in addition to passing the emissions test.
Having said that several members with MK3s have successfully got their cars through their MOT since the changes with the original maniverter replaced with a performance manifold.
At the moment it seems that the new rules are not being rigidly adhered to.