The wireless device in many systems is often the basic specification "N150" - 2.4Ghz band only.
In 40MHz (wide channel) mode the throughput can be up to 150Mbit, in 20MHz (narrow) it's limited to 72Mbit before losing anything to congestion or stepping down to lower speeds due to weak/interfered signal.
The superhub offers 3 rather odd speed settings under advanced, Wireless radio.
The lowest, up to 54, is what other devices would call B/G mode - you do NOT want this unless your kit is ANCIENT.
The next, up to 144, seems to be the default - this is 20MHz mode, N standard, dual streaming available to N300 class devices - on N150, it's limited to 72Mbit.
Up to 300 - this is the 40MHz mode - if your channels are not too congested (try Inssider free on your PC to check -
http://www.techspot.com/downloads/5936-inssider.html ), then this may double up the throughput on an N150 system.
With "OBSS" selected, it will drop back to 20MHz mode if using wide will step on adjacent channels - If Inssider shows it in narrow and adjacent signal are present but weak, you could force it to stay in wide by deselecting OBSS