the time it takes to replace a secondary air injector valve

What is your question?

does anybody know how long it takes to replace a bad injector valve for the secondary air system that puts air in the exhaust when the engine is first started, the valve is at the back off the engine (3.8) we found the problem with the test equipment the picture off an engine comes on the pump works good it leads to the valve that needs to be replaced for emissions testing and ideas?