The speakers in the top of your dash are a non-standard sized 2.5" midrange speaker. There are really only two places that you will be able to find a proper replacement for them; the bmw dealer and us. Difference being with the dealer piece it will be exactly what you have now, while ours will be an upgrade in both soundquality and durability over the OEM part. Plus a pair of our plug n' play midrange upgrades cost less than just one of the OEM replacements. Here's a direct link to our plug n' play midranges for you X5,
X5 Front Midrange Upgrade
Just so you know your car has a 10 channel amplifier in the rear left of the hatch area located behind the carpet. Each channel is dedicated to each speaker in your car and is crossed-over internally according to what the speaker is designed to reproduce clearly.
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We offer a full speaker upgrade for your car that will replace every speaker in your car greatly improving the clarity of your audio system all while keeping your OEM amplifier and head-unit. We replace your oem mylar (plastic) tweeter with a silk dome tweeter, your stock mid-range with our higher quality audiophile grade mid-range, and you muddy mid-bass with a high quality treated pulp cone mid-range. All of this will greatly improve your audio systems sound clarity and decrease your distortion levels allowing you to enjoy even louder volumes in your car. Oh, and all of speaker systems are completely plug n' play and come with full instruction guides and many with video install guides to walk you through the installation process. Here's a direct link to our
Stage 1 Speaker Upgrade for the E53 X5
Also here's are installation video to show you how to install our Stage 1 but you can apply it to any install.
http://www.youtube.com/watch?v=y25x6gIIgPE
I hope this helps and feel free to contact me with any audio related questions you may have.