Are you guys paranoid or what? It's the metal expanding and contracting. My 2001 SC2 did it from day one, my '77 Vette does it with it's new exhuast, and my '90 Camaro did it with the new exhaust. There are about 10 spots where the exhaust is attached together, welded, or bolted to the car. Not just the pipes. Heat shields are the biggest culprit here. When 2 metals of slightly different compositions are joined or bolted together, the expansion and contracting of the different types cause edges, bolts, etc, to 'bump' into each other, stretch over bolt threads, you name it. Particuarly when driven hard and put away fast, the colder it is outside, the more pronounced the effect is. If there is a service bulletin that can cure exhuast 'ticking' I would love to see it, because they're gonna have to a hell of a lot to stop that noise. I could list off cars that come over to my house that have 'ticking' exhuast systems. I've never in my life thought of it as an issue.
As far as your 'bang' sound Boka, that could be a problem, not sure.
As far as the car doing it when its warmed up, were not talking about the car. Just the exhaust pipes. There is a HUGE difference in temperature in the exhaust stream from full throttle to idle conditions, so there still can be plenty of expansion and contraction sounds from it.