That engine crinkling noise after turning car off.
 

So i'm been made aware that the crinkling noise your car makes after turning it off after driving is due to the exhaust system in your car rapidly cooling off. If this is the case, how come that "crinkling" noise only comes from the engine bay area? Shouldn't the noise be coming from throughout the car since the exhaust system runs the length of the car?

It has something to do with the metals expanding inside the engine, I think... I don't remember the reason too well.

The headers and the heat shields around it get the hottest.
About 1 inch from the head the temps easily get 1200F or higher.
From there (and the cats) back it is relatively "cool" compared to that.

All that aluminum and there's a lot is contracting. It will expand over tremendous heat and contract as it cools down. All cars do it

After you warm up your car, the engine expands and the seals & clearances become tighter. When you turn your car off it has to cool down so the sound it makes is a crinkling sound of the engine (& other components) cooling down from a fairly high temp.