Can anyone tell me how to increase the Flyff board speed by editing the Flyff resource file ( .res ) ?

Sorry to tell you stinlee, there WAS an edit to increase board speed, running speed, jumping height etc. Sadly though they are now patched meaning you can't do it anymore. FRM is pretty much null and void now because if you use it, only the user or client can see what he's doing (AKA server sided). Meaning if you go and change your wooden sword to the level 107 sword if you drop it or try to trade it, it will still be just a wooden sword. If you want to hack FlyFF I can tell you that FRM is not the way to go anymore.

You can not increase board or broom speed by editing Flyff files to the best of my knowledge. If people could do that then everyone on Flyff could just edit everything in the program files to make them better than everyone else. Also I think that every player would then have to edit board/broom speed to match your speed (I think). Either way it will never happen. The max speed you can go at with out cash shop brooms/bikes/boards and accelerator fuel (which lasts a couple seconds) is 210. There is not much of a point on trying to get higher than 210 unless you want to spend money on bikes or something. Just stay with the board/broom you have now.