I recently got a good deal on a set of SW Motech Trax side cases. I currently have Givi E21's and Givi racks on my bike. Do I just need to purchase the adapter kit for around $100 to mount the Trax? It says the adapter won't work with Givi PLX racks. How do I know which racks I have? The bike came with them already installed. From what I can tell the E21's use the PL style racks which would work with the SW Motech adapter. The SW install instructions for the adapters show flanges on the bottom of the Givi system but I haven't found any Givi racks with any flanges? Am I right?