It's also worthwhile to consider the shaping of the mountains. The ones you have appear quite sharp and pointed, which is cool graphically, but also has some geological import; I think it means they are newer, and/or made of more dense rock, but I am no geologist (so I may be entirely wrong there ).

My two cents on the above map would be that if you really intend this island to be roughly 1000 miles across, then make these mountains much shorter and include more individual peaks. The reason I suggest that is that the graphic details here really make one think of a small island with big mountains in the middle (above, someone already mentioned Hawaii). But never would I remotely imagine this to be a small continent with a mountainous massif in the middle, because then the mountains would be like 30 miles tall (again, just going off of the graphics of them). I think the underlying point is just that the visual details affect our perception of what is being represented, so you don't want us to be totally misled by the map.

Now, all of that being said, maybe you want the mountains to be unreasonably tall and generally massive, for story reasons. If that's the case, then leave this exactly as it is. But then you'll need to hit the point rather hard in the story so that it is clear that these ain't your granddaddy's mountains!

In sum, the mountains look cool, though you might think about scale and number of them, and I am excited to see how this develops further!