2001 S3 with Alpine DVD head unit with very poor radio reception

As above realy,
My car came with the Alpine head unit already fitted , The speakers are Bose so is the Amp, ( sub replaced/upgraded by me)
The radio reception has never been great but now i cant hold any station once moving, I have replaced the arial mast as it was ******** with both a standard one from my mk3 golf and now a Lexus stubby one.
Somebody on the S3 section said because the car had a Bose unit in before any other head unit would need a signal booster ?
Is this the case? Is there an Audi part or is it an after market part?
Many thanks

Thanks.
The "brain " for the unit is hidden away in the rear of the car, Im guessing the adapter will need to plug in there? as thats where the remote feed will be?