I want to go very slightly lower in the rear of my EF. I remember reading somewhere that a bloke with a VS removed the rear insulators to get a slight drop, to level out his car.

I'd like to do this, but I need to know if it will have serious effects on the spring staying located, and also if it will make s**t of noise....

It will make s**t loads of noise.
What springs do you have now?

XR8 ones. Sits alot lower than I thought it would, but I want it a touch lower in the rear. I may just have to pull them out and get them reset one day.

I have a set of superlows here, but I was going to sell them, I don't want to go that low.

one thought that comes to mind is to use the super lows with a coil spacer. Another option would be to cut a bit off the bottom of the XR8 coils, but then you can't go back from that.