Just fitted Alpine CD comander and DLS reference speakers to my MY99 5 door.
Now getting horrible buzzing noises (resonance) from passenger's side door.
Has anyone else had this problem ? It is a dealer fix under warranty ?

Yep. I fitted Alpine speakers in the front, and straight away I got bad resonance on the passenger side. Traced it to the door trim - the door 'bin' cubbyhole is separate from the main door trim but is in loose contact with it. I sealed the two together using a hot glue gun - problem solved. I wouldn't bother a dealer with it, much better to sort it out yourself - you could use any kind of glue, or even blu-tak or some foam. Strange I never had this problem on the driver's side....