What is metal to metal interference? If your referring to dissimilar metal corrosion, I highly doubt it will play much of a factor that would be of any concern. If you choose to use the lock-wire method I would recommend a .020 - .032 monel type. (Monel= high heat resistant). I dont think it be necessary to wrap it around your engine though. I would attempt to limit it to the pipe/exhaust for anchoring.