[vector1]

another thing with the one piece header flange, aluminum expands around 2x the amount of steel, so they are constantly working each other. if you can tolerate it split the flange between the pipes and use rtv or any gasket and it will work well. i split with rtv and no problems, rtv the bolts also holds them in. if you have the one piece flange, i would suggest a gasket that will have sliding properties like copper to hold together, but the two dissimiliar metals will work against each other, so maybe enlarging the header bolt holes will allow some movement.