Stretching it will ruin the quality. It's at an almost 16:9 ratio now, stretching it wider will warp the image if you don't increase the height. The height unfortunately is the max the forum allows for a sig.
It's a simple image though, so I can reorganise the text on the image for you. Or, if you have the image without text I can add it in and keep a 'longer' image for you.
Mate, put it this way. If you can make it look cooler, do it. Ill leave it in your creative hands. Creativity is unfortunately not my strong point.