Ok, I have just flashed my sparkle card with the Gigabyte GTS bios from MVK tech and its gone fine. I did change the clocks to stock GT clocks first with Nbitor.

I had to change the Device ID in the drivers to get them to install.

And it looks like it made no difference, the extra processing pipes seem to still be locked.

http://horrorwood.googlepages.com/GTS2.JPG

I did leave the GTS volts as they were, so I will try overclocking now