Tapping from an exhaust leak is typically at the exhaust manifold gasket where the exhaust connects to the engine. The tapping sounds oddly metallic, gets louder as you open the throttle, and often gradually gets quieter as the manifold heats up.
My favorite way of finding exhaust leaks is with a cold engine. I duct tape a shop vacuum hose to the exhaust pipe, set up the vacuum to blow, and listen and feel for the leak. It will be obvious enough.
35 years maintaining my own cars