I have bought a secondhand all dancing dab/bluetooth dd radio, and im wondering... and guessing there isnt a dab aerial or take off point on my 2007 140 se passat - so whats the best way to go about it ? and where is is the existing aerial - its not on the roof so im guessing its on the back window - which.. means i shouldn't try to put the dab aerial there should i ? and if not .. where ?? and over and above all this, am i gonna have any probs fitting the kenwood dxp406dab into the passat ?
Also, i am aware of the piggyback fm/dab converters and have heard they are not much good ?

so - where do i look ? where do i start ?