Type 4 exhaust manifold leak

[Panayotis Nikas]

Hello everybody ,
I use a bas 4-1 exhaust system on a type 4 engine, the exhaust it self has great sound and helps the engine achieve great power.
The problem I am having is that its impossible to seal the no 3 cylinder exhaust port with the manifold, it just wants to leak and make that dumb sound.
I have seen the ratwell article on sealing the exhaust but it dint help me since I don't use the stock manifolds.
I have tried using permatex exhaust sealant but it cures it for a day or two an then it does the same again.
Does anybody have a recommendation on a better method or perhaps a better sealant ?

[Wreck]

can you put the header upside down on a flat surface and check the sealing surfaces are even . If it's an oval port head are you annealing the copper gaskets ? you can try using maniseal CRC 5061 . or an equivalent sealer on either the square port gaskets or the oval copper gaskets .