I think the speaker in the drivers side front door of my 380 SX is faulty. Can someone tell me if the whole trim has to come off to replace it? If so is it difficult and should I get the dealer to do it?

yep , very easy... takes about 15 seconds :)
a couple of screws , and there is just clips around the edge....

Thanks Brad. I'll get to work at the week-end.

Four screws to be precise, one under the door handle, one under the little cover in the pull handle, and two on the edge of the trim, one on the side and one underneath (both hiding under little plastic flip off covers).

Maybe a tad more than 15 seconds!

Just wanted to list this info somewhere, The door speaker can be replaced with any 380 door speaker, as can the 6x9 in the parcel shelf.
But the tweeter from the GT - so I'd guess any with the 6 stacker and the MFD, have a different speaker to the base model, it fits in the same slot but the loom plug differs.
The base stereo speaker is just a tweeter, the premium stereo has a tweeter and a midrange, about 2.5".....

Just wanted to list this info somewhere, The door speaker can be replaced with any 380 door speaker, as can the 6x9 in the parcel shelf.
But the tweeter from the GT - so I'd guess any with the 6 stacker and the MFD, have a different speaker to the base model, it fits in the same slot but the loom plug differs.
The base stereo speaker is just a tweeter, the premium stereo has a tweeter and a midrange, about 2.5".....

a 380 speaker? as in a speaker from a 380? (sorry noob question, but something that id been considering for a while). I have a 380 SII VRX

Errrr, this is the 380 section...???...isn't it...???
:s Sorry what is the Question

sorry, more what the question was ment to ask is the speaker size in the doors specific to a 380? or is there another speaker that is available to fit in its place

They would be about a 6 inch speaker, with a small weird baffle thats part of the speaker.
I couldn't mount the 6.5 replacement directly to the door, I had my old 6.5 inch split speakers mounted on a 12mm MDF Ring, no problems there. I think they were about 70mm deep from memory.
I didn't run up against any clearance issues.
I wouldnt get too excited about aftermarket speakers if you just power them off the Head unit, I have a pioneer double Din in mine so theres arguably a bit more power there, But I dont have a MFD to worry about.

I just looked at these http://www.performancecaraudio.com.au/products/hertz-dsk-165-speakers.html
With a 93 Dd effiency, I reckon they would go fine off a VRX H/U, only 68mm deep too, but bugger If I know where to get them, the Hertz off Ebay I think would be somewhat questionable, perhaps OS.
And I'd mount the tweeter at the base of the A pillar, point inward. Not in the OEM Tweter position. For staging.

With not a lot a people yet to go fully after market with the 380, you'll have to do a bit of pioneering.