There is an aerial amp in the standard stereo so when you fit an after market unit you have to add a booster or the reception is shocking (PC5-52 or PC5-90 depending on male or female aerial socket).
Was looking at a shark fin for mine but unless its a genuine oem one not going to bother. Think im gonna trim my standard one down as seen a few and it looks good and if they work the same then be happy with that.
PS the blue wire is to power it so connect to remote live