Roof arial

[Keeff]

my radio is rubbish as soon as I go out of town both DB and fm. If I use the car a three year old Vauxhall it works on fm ok. Taken it back to the dealer and they say it's normal .i was thinking of fitting one on the roof but don't want to drill a hole because it's on a lease but could I fit one down through one of the holes for a roof rack with a 6 mm thread then connect it in the van above the roof lining .Anyone had the roof linning down and thinks this could work?
Does the vw head unit have two arial connections one for DB and one for fm as I would be happy to just connect it to the fm.

 

[Keeff]

Just had a look on the net and I can get a magnetic mount arial but can anyone help with the connector I need on the end to save taking the head unit out before I get one. If it works I will give the roofrack fixing hole a go.
Thanks

 

[Fish]

@Absolut5