Today I have developed a strange rattle coming from just behind the steering wheel which is only apparent at full throttle, it generally starts when im coming on boost in 3rd gear and continues in the other gears also when on boost. There is no vibration in the steering, just the rattle, its as if something is really loose?

If I turn the steering full lock clockwise for the last 5th of a turn there is a bit of resistance in the steering, but if I do it anticlockwise there doesnt seem to be any resistance. Im getting worried that it could be the steering rack, altho the rattle is definately coming from the behind the steering wheel and I would like to think on 4 year old car with less than 40k miles the rack wouldnt be gone already?

Anyone any suggestions as to what it could be?