Okay I emailed OWC's tech support. In the meantime...

Metronome indicates that my bus speed is indeed set to 100MHz. I double checked my jumpers and they are correct for that setting (jumpers 5,6,8, and 9 set). TattleTech, on the other hand, says the bus speed is 76.73MHz (with the CPU speed at ~500MHz). Not sure which to believe.

I tried slower CPU settings (such as 350MHz and 400MHz) in both OS X and OS 9 and the system still reports 650MHz (OS 9) and 500MHz (OS X). It's like CPU Director has no effect on the CPU. I'm sure the INIT is loading at startup because the splash screen shows up.

@waynestewart: did you ever get yours to run at full capacity? I'm starting to wonder if it actually is an extension conflict because CPU Director is essentially useless. But it's also useless when I boot into Tiger (10.4.9, the last version that CPU Director apparently works with) so I don't know what to think there.

Thanks for the responses so far!