Yeah a higher FSB gives you better performance since it will essentially overclock everything, as skahtul said. however running all of your components out of spec will increase the chance for something to go wrong, meaning your CPU may be stable at 155 FSB but your video card may not be able to run on such a high AGP bus.
First try to determine the limit of your CPU by upping the FSB on the default multiplier then try different combinations that will give you roughly the same speed (ie 150x11.5=1725, 157x11=1727) and see how high you can keep the FSB while keeping your system stable.