In fact GT supports 160Ghz bandwidth but in practice I have not seen any benefit even from 10 feet away on my phone or laptop connection speed.
You also needs a client that supports 160 MHz channels, and you need to be in a region where DFS channels are available, and you need a fairly uncluttered 5 GHz band.
I've seen at least a 200 Mbps performance gain on my laptop when switching from 80 MHz to 160 MHz - hard to get exact numbers since I was hitting the Gigabit bottleneck of all my other clients on my LAN when I was connecting my laptop at 160 MHz width.