Installed an Alpine 9811 HU yesterday.
First audio thing I have ever done on any car haha. Anyways, the install went very smoothly, and I have a Legacy pocket with a Profec B inside underneath the head, so it's all very clean. My impressions were that the improvement was well worth the price. Through the stock speakers, everything is louder and clearer, and the MP3 compatability is a perfect replacement for the 6-Disc changer.
What do you guys think I should do next? Speakers? Sub? Amp? Let me know!