Well that was a bust... I asked the eBay guy about replacing the stock head unit with a decent hi-fi one and he said:

Quote:
Sorry, I am big into leaving stock systems alone. I cannot help you with your infomation request. I have seen lots of aftermarket attempts at head replacement and I do not approve of any of the setups. They look terrible and sound the same or marginally better.
Regrets,
Charles

Very surprising response from someone who appears to run some kind of customisation business - clearly not a man with ears though