OK, this is a bit of a weird one!
 

Firstly, imagin what I mean by a sort of 'springy' noise, like if you had a metal spring held at one end, then let the top end wave back and forwards, sort of 'twang twang'.
Got the idea?! right, well my classic turbo has got this noise coming from somewhere to the right and below the steering wheel, inside the dash, as you drive and corner or brake, its driving me nuts! Doesnt do it when the car is stationary, but its loud! can be clearly heard in the car. I have dropped the lower dash on that side but cant see anything that could be making the noise. Of course its kind of difficult to look under there as your driving (!)

I know its a long shot, but has anyone else ever experienced this?

The problem with car noises is that, since the car is effectively a sealed hollow box, where you HINK the noise is coming from may not be, if you see what I mean?

Anyweay, having ruled out the under-dash, try the following:
Aeriel fitting point.
Inside the doorcards.
Under your seat.

Take a mate for a spin and ask him/her to try different seats in the car.

I thought I had a squeak from the drivers footwell - as above, a mate found it was my seat belt release button (sorted with a spray of WD40 :) )

I had a similar noise on a BMW, had to spray WD40 on the steering connection under the bonnet and it went away. probably not the same tho.

Thanks for those suggestions, its driving me nuts!

Wiper arm spring?