Abstract: A heat exchanger manifold comprising tank and header members secured together, each of the tank and header members having an interior surface facing the interior of the manifold. The header member comprises at least one raised surface feature on its interior surface so as to define longitudinal channels in the interior surface of the header member, and longitudinal passages within the manifold. One or more openings extend through the header plate and the raised surface feature. The width of at least one of the openings through the surface feature is less than the remainder of the opening, so that a portion of the surface feature defines a tube stop that limits the extent to which a tube received in the opening can extend into the interior of the manifold.