Haven'r heard any of those. But with 30+ years in an industrial environment - Not so sure my ears can detect those noises anymore.
Chirps and squeeks generally aren't exhaust - they're generall metal on metal - That could be normal chain noise, could be brake noise, or, any other source where metals contact. If you hear a noise on under certain circumstances, it's generally related to the conditions that are present at the time - i.e., if you hear a noise ONLY in second gear, I'd lean toward gearbox noise. Keep in mind chains are noisy buggers - even when lubed to the max and aligned perfectly - When you're along side a barrier, wall, bridge rail, that noise is amplified.
