Do I need to replace my exhaust manifold?
 

I am replacing a few gaskets because my car leaks oil and this should take care of it, but I noticed what looks like a crack on the exhaust manifold. Does it need replaced? If so, can I use aftermarket or does this need to be a Honda part?

It also looks like it is missing a cover. Is one on this car? I have a 1997 Honda Civic EX.

Third question: While replacing the head gasket should I replace the spark plug tube seal and can these be aftermarket?

Thanks for all the help!!

[not sure why the pics are upside down...tried to change it with no luck]

Does the car sound noticeably louder?

Tube seals do not need to be replaced unless they are leaking. If you are worried about it, just replace them. After market is fine.