The current "server booster" icon is the star coin from the bottom screen ui when you're in levels. It's around 32x32 which clashes with the other icons (powerups, etc) that are 16x16.
For this reason, I would suggest replacing it with the star coin icon from the "Complete" text graphic on the worldmap (which appears when you get all star coins in a world). It has a resolution that is almost 16x16