If you link me to the original images that were used to make the current background, I can try to find larger versions of them. If I do find them, then yes; I can make the background image larger. If not, we can work on a new background, if you want to try that.
I don't have the exact link to the original image as the founder was the one who created the current background. Luckily, the aforementioned has been uploaded onto this wiki: File:The Group.jpg (most recent size is 576 × 441 pixels).
The new background image looks amazing. I really appreciate the fact that the middle of it is now blue instead of the original white. And the transparent shading on the left and right sides is a creative addition.