There is a ton of threads on this. Search and you will find them.

I replaced my air suspension with Blistein HD yellow shocks and Eibach Pro springs and could not be happier.

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01' e53 X5 3.0i - 140k miles
06' e90 m-tech 330i - RIP
09' e82 135i 11.3 1/4 mile @ 123mph - RIP
06' e53 X5 4.8is Le Mans blue - 400hp/410tq