most aftermarket extractors have a hole for the oxy sensor at the end pipe just before the cat. Its moved as the oxy sensor has to be positioned in a place where it can read the exhaust fumes of all cylinders.
If they're designed for an efi car, it should have the hole for the sensor - although on some designs, it might be further back or forward than the factory ones ( depends on design differences ) - which might make it harder to spot . . .