it will run with it off, using replacement value....
that is sh!te on naturally aspirated engines already but there you got throttle body potentiometer so it can "guess" how much air is going in.
add a turbo and you got another variable.... so the replacement value will be even less close to the real deal...
which will result in:
loss of power,
lower mileage,
probably MOT failure,
check engine light coming on....
and finally you'll f**k your cat.