From what the picture show, this looks entirely normal for an older
car. I suspect someone checked the valves (does the 2000 use hydraulic
lash adjustment?) and did a sloppy job with the gasket. Also possible
is a slow leak from the distributor seal. If it bugs you, buy and
install a new gasket, then give the block a shot of engine cleaner.

Unless you have more to go on, I'm thinking the exhaust noise has
nothing to do with this.