I have a 1984 Z-28 with a slightly built 350. I have headers with a Flowmaster exhaust system. No catalytic converter. 3 inch exhaust. I know exhaust is going to smell but when I drive my car there is always an exhaust smell. When my wife and I take it on a trip we usually end up with a headache. There are no open holes in the firewall and no exhaust leaks. It's getting harder to convince her to ride in it with me. Any ideas?

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There has to be an exhaust leak. If you're sure there is not, then run a cat. That should reduce the smell.