Some people say there might be memory error by allowing port number to go above 15. That is not true because AppleUSBXHCI actually read hardware registers to allocate memory, for example activeDeviceSet is constructed from Max Device Slots value in HCSPARAMS1. Port limit checks can be safely removed. People might wonder why the first place to limit ports is in AppleUSBXHCI not AppleUSBXHCIPCI. Well, AppleUSBXHCIPCI constructs ports property and calls super class (AppleUSBXHCI) method to enumerate ports. If ports property is defined, only ports listed will be constructed. If no such property exists, AppleUSBXHCI goes through all capabilities defined in the controller. That means by deleting all ACPI USB port definitions, all ports will be enumerated!