i had a set of hookers that leaked.it was suggested to cut the flange between the ports so that the header would bolt up flat to each port. this was on a bb, it did stop the leak. on another set of hookers there was no tube extending pass the flange, basically there was lip to push against the head. we used a mig welder to build up the lip so that it would push the gasket against the head, this worked also. if you do this you will probably have to lightly grind (i used a flat file) the weld to get it flat. use a straight edge, lay it across the weld and you can see what you have to do to get the lip even and flat to each other.