Low speed from analog input (AX2550)

We have switched to an AX2550 controller from a Robot Solutions RS160D 160Amp controller. The problem we are having is that under the same conditions, we are not getting anywhere near the top speed that we are able to achieve with our previous controller. We prefer the AX2550 as it is friendlier to use. Is there anyway that we might be able to achieve greater top speed from our analog 5v input? Can some parameters be adjusted through the terminal? All the available parameters are set at their top range. We don't seem to be having any problems with torque, as the wheelchair can accelerate from a standstill and will not blow the 100amp fuses that are inline. Any help would be much appreciated.

There is a known problem if you connected the controller with a PC running an old version of the firmware (1.9d). The power output gain would mistakenly get loaded with a low value.
Make sure you have the latest version of the utility and that the output gain is 100% in the Power tab.
If that is OK, then the next possible cause can be your analog command not going all the way to 5V.