A mounting bracket is something we recommend. We have several mounting kits available for the Road Glide Fairings and Batwing Fairings models. You can also create your own customize mounting bracket; just be sure you can still fit your amplifier.
Side Note: Do not mount your amplifier directly on top of the stereo or the stereo's mounting bracket. Why? Over time, you’ll damage the stereo with heat transfer. Also, you will void your warranty if you do so.