Ford: exhaust leak, exhaust ports, seal points

Question
1989 302 hi out put mustang. has leak on the right side.header gasket has been replaced. can find no hole in header.can onley hear it when car is under a load.ford dealer has gave up after $400.00. tia

Answer
Most likely slightly warped head or header.  Best recommendation is too remove the header with a long enough straight edge make sure that all ports are flat and even with no slight warpage.  Use the same method on the head look for daylight at seal points around exhaust parts.  If you find any warpage on the header it will need to be replaced because header can not be surfaced.  If there is warpage on the head and it's not over .040 remove the head and have the exhaust ports surfaced at a machine shop some napa's have these.  If over .060 you will need to replace the head completely.