once again i use my mates example.... purely because the sound he gets is awesome...
he got a Siemens VDO high quality head unit, let me know if you want the model, its 4x45w i think.... but dont let that fool you....
has (i THINK) 5 inch splits in the front, 6.25" in the back, the back is kenwood, cant remember the fronts, but i can find out for you if you want, no dramas.... all up about $700 installed, but shit it sounds so good!!