Install is not that bad if you have mids that fit. Polk, MB Quart, Infinity, and JL Audio. May be some others. I swapped out my tweeters and left the mids in my current setup. The tweeters make a big difference in sound quality. I am going to either keep the factory mids or swap them out for some 2 ohm Infinitys.

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2004 BMW X5 3.0i - Mine
2011 BMW 328i xDrive - Hers
2002 BMW 325xi - waiting for a new owner