OK i just came back from doing a few revs and driving around the streets. Im 99% sure its really the exhaust thats doing the rattling. I think its the hanger thats touching onto something. It rattles like a little bit once in a while on idle now, but it still resonates/vibrates around 2000 rpm. Hrm gotta go back to the workshop next week. Unfortunately its public holiday.

Tried reving stationary; no rattle/resonance