I've recently done a oil and filter change on my NC29 and has been running alot better for it, but now when it reaches about the centre of the tempreture gauge a high pitch ringing pops up, its not the fan becuase you can hear that sepretly. It could be from either around the water pump area or the radiator (can't really locate it). It is only there while the engine is running. The tempreture never goes above halfway so thats not my worry as the radiator had a complete flush and new fluids not long ago. Any ideas?

Thanks, Chaos

If it's when it's hot I'd go for the radiator breather or overflow bottle cap? (I get the same thing on our little mini! )
Worth a try.