[Damien]

If you are using stock stamped valve covers you need to make sure the gasket flange is straight and not warped form over tighting. Use a hammer and a block of wood. On the intake end seals, I always use The Right Stuff. Its made by Permatex. Its a little spendy, but well worth not having leaks. Throw the rubber end seals away and use a bead of the right stuff.