ram timmings advice!!!

[badaphooko]

I currently have my xp2500 o/c to 2.25ghz (11x205)stable. my cpu voltage is at 1.75 and my ram volatge is 2.8. my ram timmings are at 2.5-4-4-7. i have corsiar xms 3200 cl2 ram. My questions is i want to squeeze the most out of this setup, what would be the most agressive timmings to get the most aggressive overclock out of my system? and is it possible too shoot for 220fsb whith this rig.. my temps are at a cool 38c under load. also any other helpfull tips would also be appreciated.