I did the L12 Mod as well. Before I had a 2600+ ( 133 * 16 ) afterwards a 2600+ with 166fsb and 12,5 multiplier!
But it didn't help me to raise the FSB any higher. I also did the VDD Mod and my Ram is Corsair PC3500.
So why doesn't it work ? It just doesn't boot. Keeps doing long beeps.