i use chemicals from my work, but brake clear areosol and a wire brush and elbow grease!!, jet washing wont really do alot unless there caked in mud, i would say if you have the old flexi brake pipes connected, leave them on whilst your cleaning and squeeze the hose closed with some mole grips of brake pipe clamps, this will prevent sh@t going into the cylinder and also the thread where the pipe goes!!! done my 8v a few weeks ago well worth while mod!!
Gaz