If your limited on budget, replace your factory deck. Adding a cd changer (after buying the adaptor) is more expensive and wouldn't sound as good as a new deck.
---Buy Kenwood or Pioneer (if on a budget); Alpine, Nakamichi, Clarion, or Eclipse if you can spend a little more.
Speakers= Infinity,or polk audio (5.25" replacement size)
As far as install goes, no you don't need a dash kit. The BMW factory head unit is standard single din size (same as aftermarket).
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