Advancing your cam by 4* will effectively change your intake closing 4* earlier (in the case of the 211 cam, from 45* to 41*). This will increase your low-end torque, decrease your top-end power. Whether it's something you should consider depends upon your goals. If your current setup feels a little 'lazy' on the low-end, this would be a way to give it a boost without having to change cams. It would get rid of some of the typically seen dip you have between 2500 and 3000 rpm.