Using Silicon hoses as exhaust pipes?..

[chappers14]

hey, as per the title, i was wondering is it an MOT failure if you use silicon hose as exhaust piping, as it can be used in the engine bay surely it would be temprature resistant, and has pressure reisitance too?

i'm looking to add a back box my self, and would like to position it in the centre of the bumper, but it would be awkard to bend a steel pipe into this position, that's why i'm going to use silicon hose as its flexible and durable.:idea:

Advice would be appreciated,

cheers G