Hmmm, I just put my Monster Mats on top of the regular mats. Seems to work fine and no "bump".
Today my dealer gave me "free" front / rear rubber mats and the cargo mat. I went to my garage and put myself to work. In around 20 minutes i got all the mats and the cargo mat to fit perfectly. How you may ask.....by using a screw driver and pliars and breaking off the round attachments. This leaves a round hole where the original floor mounted oval attachments will fit and actually block the mats from sliding (even if, at has already been said, they are so heavy they don't move). The great thing about this is that now you don't have the "lump" due to the round attachments resting on the oval ones. I'm so proud of myself
Those are the European mats. Monster mats are made somewhere in North America and only sold in North America. The European mats are made over there somewhere and only sold there. These things are way too heavy to ship here based on their value. It is cheaper to make them locally.