Which MX5 donor?

[waynes world]

Talking on exhaust CAT`s, what year do they need to be fitted from?

When you go for a n MOT with a kit car and has an engine that needs a CAT on the original car, will the MOT tester actually know what engine you git fitted, only ask as when i have been in the past with cars they just want to know the engine size.
I ahve taken a diesel car before which was a petrol and they didnt bother aslong as they knew what fuel the engine was running.