take your car to and empty car park and put on full lock and drive off slowly(one way then the other) if you hear the noise then it is the cv joints , if you can only hear it when the car is going at speed and u are going around the corner it could be your anti roll bar bushings and the knocking is the bar slapping against the suspension sub frame. anti roll bushings are only a couple of quid from a good motor factors but are a bugger to change, cv joints are a good bit dearer

tiaxxx