Nice. If you're getting that, I ought to do well.
I've had one of the very early VGA Silencers (the original Rev. 1) on my card, with some teeny aluminum BGA ram sinks on the memory, and gotten reasonable close to those numbers (450/375 or 380 rings a bell).
I'd imagine I will be able to push the memory a bit more with the new Silencer, as the cooling will be better than those lil' aluminum sinks.
I'm not really expecting a better O/C on the core, but would like to see better temps where I've run it previously. If I can pull another 10 MHz I'd be very happy (and a bit surprised, actually).