How does an EK9 steering wheel not have a open spline hole behind it? It must not be the OEM EK9 wheel because that is impossible. The OEM wheels have a metal skeleton inside of them and the metal branches join together at a flat thick metal base in the center behind the air bag where the spline hole should be. So did you buy an OEM EK9 steering wheel or a AFTERMARKET steering wheel that was advertised for EK9? If it's an aftermarket steering wheel like Momo, NRG, Nardi, etc, then you'll need an aftermarket hub/boss kit that is properly made for the car so that the hub's spline hole will fit the steering column. But if the wheel you just got is OEM EK9 steering wheel which miraculously doesn't have the hole behind it, then you CANNOT attach an aftermarket hub/boss to it. It just simply doesn't fit because they are both female connectors.