First of all thank you to CyclingBroStyle for posting a solution to the speaker rattle problem. I just wanted to post instructions how i fixed it because the noise was driving me crazy and I hope this helps other people with this issue.
Step 1: I found that the cover wasn't easy to just lift up. The speaker cover has 6 clips as shown in the pic below. I used a card to wedge under the speaker cover and to push each clip in. I started with the bottom left clip (closest to steering wheel) I found that I had to push the card into the clip in order to release it and simultaneously lift the cover with a little force. Eventually one at a time, I released all 6 clips. It could be that you can just lift up the cover with pressure but it didn't feel to me as if it would work without breaking the cover
Step 2: Once I lifted the cover off I used felt tape to cover the plastic tab on the top of the speaker cover as shown in the picture below:
Step 3: I then covered those two plastic contact points by the speaker on the sides of where the plastic tab from the speaker cover connects to pictured below:
I then popped the speaker cover back in and now the rattle has gone away. I tested it in Sport+ mode under heavy acceleration and when raising the volume of the stereo under different frequencies.
This is a link to the felt tape I used:
https://www.amazon.com/gp/product/B01455QMX4