The all in one exhaust manifold/catalytic converter on my z10xe has got a hairline crack about 6cm long to the right hand side of the lambda sensor. This is not blowing at all and the engine sounds completely the same as always. I only discovered it because i was changing the heatshield that had rotted round the bolt holes and i dont know how long its been there. The crack looks fairly old as it is rusty . If it is not blowing, will it be ok to keep driving the car with the crack and is it likely to pass an MOT if i put the heatshield back on and forget about it? Will it survive the winter or will it get bigger? I am a student and really cant afford a new cat if i can get away with it.