crank pulley

I'm planning on getting an Agency Power lightened crank pulley. The only other modifications I've made are a K&N drop-in filter, a silencer/snorkel delete, and a radiator cover. I've read a lot about this mod, and there seems to be a lot more good than bad. The only thing that scares me is that...

Whats the best way to get the crank pulley off on my '03 WRX?? I already broke a strap wrench trying to hold the pulley while we loosened the belt.. no luck. help!