Yeah, that is a minor downside, but if you think about it you probably would be changing the block in the future anyways. And the MCP350 pump side of the combo is fully upgradable with an aftermarket top and there is also a very simple solder mod you can do to the MCP350 to convert it to a MCP355 motor (from 10 watt to 18 watt motor) as they are the same motor on the pump. Martin's Liquid Labs has some good pics of the mod area in their review of the Apogee Drive (the pump/waterblock combo that comes with this kit). This mod could also be done on the present setup to get you a little better flowrate and pressure also.