I brought the JVC KD-LHX501 head unit from a mainstream motor accesories store (Halfords) and had it fitted in the price. Now I've checked the wiring but am not sure if it's been done correctly as I've read in other posts that the RCA preouts should be used. Are these on the left of the diagram if so they have not be used. Does this matter as the sound from the unit is much better then the stock unit.

The only connections used was the big main block of wiring and the antanna wiring which will be done when I go back and pick up the adapter which is needed.