Link speed under QOS node tab in Replication section

Hi all,

As per our conversation with Dell for a few months ago, they mentioned that if QOS node for wan replication is setup to  maximum 1Mbps, therefore the actual is only half from the setup. In other words, I would obtain 500Kbps only. Is is true? The second question is, why the link speed shows 1.54 Mbps since the QOS node is setup at 1Mbps? The last question is how do I know the link speed of wan replication 1Mbps if I wanna change it? As you can see, the current speed now is 1.54 Mbps. The link speed is depend on what? Can you please tell me how to do it?