I am putting my engine back together and I have everything on the block but the intake manifold. My master rebuild kit came with 2 types of seals for the intake manifold where they mate to the heads, metal and fiber.

I would like to know what would be better suited to use. Is there a significant difference in how long they last/performance or is it just up to what you want to install? When I tore the motor down it had the metal seals in it, but if the fiber ones last longer/perform better I'd rather use those.