Easy stereo upgrade
Thought I would throw this out...works great. If you have a D90 with 4 speakers (2 in the doors and 2 in the rear) all you have to do is swap out the speakers for a set of 4 M.B. Quart 6.5" speakers which you can pick up off of ebay for about $90 bucks a pair. Using the stock head unit is fine. The only tricky part is you have to use some kind of nibblers or sabre saw to open the stock speaker holes up a little since they are 5.25"...the 6.5" MB Quarts come with templates so drilling for mounting holes and cutting is simple. Then, buy a portable XM Radio unit...I have an XM MyFi unit...the newer Panasonic unit (portable) goes for maybe $100 bucks also on aforementioned auction site...So...with CD quality source from the XM unit and awesome speakers, you could be enjoying some really great tunes in an afternoon...The Quarts have a lot of capacity so you can run em louder on the road and hear great. The portabel XM needs no additional antenna and broadcasts into your stock radio. Works like a charm and you won't believe the improvement in sound quality.