i just read that the oxygen sensor in the exhaust manifold adjusts the fuel injection to lower emmisions and i was wondering if at times this could lower fuel efficiency or power. and also, will the car be considered unroadworthy with it disconnected, if so wouldnt this make all cars with extractors unroadworthy assuming there is no other way to hook up the oxygen sensor?

umm oxygen sensor measures the exhaust emissions from the engine in order to determine whether the car is running too lean or too rich... Ur EFI car needs an O2 sensor for correct reading and operation. Usually iwth extractors they drill a hole for an o2 sensor. My pair has an o2 sensor in it.

k, good, thanx, i rather it that way then