Ultra XL ram

I've had ultra XL 2x512 ram now for about a year and I've been unable to run 2-2-2-5 even at 200Mhz. When I contacted Ultra about this they said that this ram is not designed to run 2-2-2-5 and that i should just run 2-3-2-5. Which works. I'm currently running 2-3-2-5 at 208 Mhz. Is there something I'm missing? I've read reports of this ram going as fast as they claim and taking 2-2-2-5 timings. Can anyone help me out with any advice or do I just have a bad set?

You probably need to bump the voltage up a little from stock. Do you know what chips the memory uses?