You can certainly fit the Maxton Design ones with the bumper still on. Bit fiddly in the corners under the fog lights but doable (have fitted two like this). Reckon the World of Carbon one would be the same. Have only been involved in fitting one of those, and that was to @Fish's van, and the bumper was already off to do other stuff, but the principle of how it fitted is exactly the same, so can't see why you couldn't do that one with the bumper on as well.Perhaps a silly question, but did you remove the bumper to fit it?