Can you give us a heads up on how you finally installed it. I have a similar system corei7, GT650m 6gb RAM etc. I pretty much gave up on it while working another project. I also like yourself have installed Cuda/Nvidia on a Core 2 duo with a GT230m got 2292.0 PMKs/s. I have followed Samiux's tutorials successfully in the past for that one.
If you can give me more detail on what you did then I can run a benchmark in pyrit to compare with you. I agree with you those figures are a little disappointing .
Thanks for your help