Doesn't sound like loose bolt...as loose bolt will rattle etc... this is banging noise. But you never know lol
Yea, best idea to stick it on the ramp and try to wiggle things to see whats loose.Hopefully nothing major mate!
Saying that...exhaust looks pretty solid! Best idea to get 2 people...one to shake car and another one to hold different parts under the car to see if you can configure it out that way