The O2 system can be sensitive to changes in length of the wire, and is why most have issues with the universal aftermarket sensors when they splice them into the factory harness. It would probably be better to weld an O2 bung onto one of the down pipes and keep the current O2 sensor in the same place.
If you haven't seen them,
Stage8 Fasteners are supposed to put an end to bolts coming loose.
