A question for anyone that knows i have a mk 4 gti 1.8 turbo agu engine the car has a straight through stainless mongoose system with no cat just been for mot and failed idle test. I have now bought a new cat to go on but this has 2 threaded holes in it either side of the cat which i belive is for the lambda sensor as i do not have a sensor can these be blanked off as i only need this to pass mot and will be back off the car after the mot help please.