thank you for all the advise given, just to give an update on the noise.
Took it to the garage who looked after my Skyline, and asked him to check the front Subframe bolts for me, Which he did then and there (cos hes a good egg), the rear ones on the front subframe where tight but when he checked the ones at the front of the subframe, they where down to about 40nm, so he torqued them up for me.
It seemed to be a quiter but there was still a knocking.
Well i have now also changed the Wheels to 17inch and the front of the car feels loads better, but still has a slight noise.
Andy at SP Autos (the chap who looked after my Skyline)is going to check the Rear Subframe this week for me.
I'll give up an update once this has been done.
Thanks for the advise.