I heard about a recall on exhaust manifolds due to cracking problems in honda civics... does the 99 honda civic lx 4d sedan qualify as one of those that was recalled?
cracked exhaust manifold on 1999 Honda Civic
You could give the dealership a call with your VIN, and they can look up whether you are eligible for any recalls.
Car is probably too old to be cover by any recall, but I have seen these manifold crack. They are available aftermarket (from other sources than Honda).