The article you linked to shows inlets for air-cooled engines. Your Rotax 915IS is (mostly) water cooled and should work without any issues with the cooling setup on your aeroplane, if everything has been hooked up, cowled and installed correctly. From the description I get the impression that you are running a partially non-standard engine installation in that there is a reducer(?) involved? I wouldn't trust internet wisdom but take the aeroplane to a knowledgable aircraft mechanic. Because it is an experimental, you cannot rely on the basic information and experience from the factory and others, you may be involved in some (light) test flying along the way, even if you're not aware of it.