C6746 (456 MHz) UPP BW

is UPP max bandwidth different between 300 MHz and 456 MHz versions of the device.  TRM says max speed is 1/4 CPU clock (sec 29.2).  The DS says 75 MHz (sec 5.23.2), but is that for 300 MHz part or a limitation of the UPP itself regardless of CPU clock?

Regards.