De cat 986 issues ?
 

Hi there.

Both my silences have holes in now. I’m not sure if I should just replace them or maybe De Cat them. They look like cherry bombs so I assume they are the catalytic converters.

My question is if I D - cat the exhausts will it still pass the MOT and is there a plug-in to let the system now things are okay, so I don’t get a constant engine fault code?

you will need to replace them if you want to pass MOT. If in doubt, call a local inspection station.

Im not sure about on the Boxster but generally on most modern vehicles you have up-stream and down-stream oxygen sensors.
Meaning one sensor reads before the cat converter and another reads after it.
If you remove the cat, both sensors will get the same reading which can sometimes flag an issue to the computer that the converter is faulty which will lead to not passing MOT

Sometimes there are ways around this but likely none of them would be deemed legal by your local MOT inspector.

-Matt

Depending on the MY of your car, if your car is running RoW dme programming, which I assume it is because of your use of MOT, your secondary O2 sensors should already be ignored by the DME. Therefore decatting should not throw a code.

Can you start the car without pressing down on the clutch? If so, you're most likely RoW

MY 03-04 Boxsters have warm up cats (upstream) and exhaust cats (downstream).

I suggest boxsa.net as it is UK based and those that answer there will be more knowledgeable about the MOT issues.