Do you mean megabits or megabytes? If you really mean megabytes, that's a 160-250mbit/s data rate on a 2-stream AC AP, which is believable 802.11ac performance depending on your settings.
What channelization are you using? 20, 40, or 80MHz? What kind of clients do you have? What are you using to test throughput?
(It's possible the hidden SSID you're seeing is the mesh backbone if you didn't disable mesh on the AP's. It shouldn't matter though — it ought not to have any impact on performance)