There is no way the stock Suspension (new GT or ANY Other stock motorcycle) is ready for a 300lb rider... No matter how you adjust it. It may feel fine, but if you had the appropriate springs for your (Our) weight it would feel even better and certainly be safer. You just dont know because you have not experienced it.
Go to youtube and search out Dave Moss. He has several different channels I believe. A good place to start is Two Clicks Out. If you watch a bunch of them you will learn what to look for and how to get it. And he will tell you why it is unsafe without the proper setup. Here are some I have saved. Just keep watching and watching and then it will click. And NO, you do not need to join anything, just watch all the free stuff. Of course, if you can afford it. Pay up, I bet he is worth it.
And here is a post from Batgirl on this site that I just read. She had Dave work on her bike.
https://www.tracer900.net/topic/7802-trip-to-the-dragon-and-bike-mods/
https://www.youtube.com/watch?v=3FeZJRiAXRk&list=WL&index=93&t=0s
https://www.youtube.com/watch?v=vzz5wX7P-5c&list=WL&index=92&t=0s
https://www.youtube.com/watch?v=3qA3Ja7yxcQ&list=WL&index=94&t=0s