I have the original air bag suspension, haven't had anything go bad in 117,000 miles. I rebuilt front and rear suspension at 90,000 miles-huge improvement. You can see what I did in my mod link. I drive hard and don't see the benefit of coilovers.

Handling is a personal preference. The X5 understeers with stock suspension and it is very hard to dial that out. The 4.6 is no exception. The changes I made changed handling to a slight oversteer condition. That's what I like. You also need to bear in mind that best changes are specific to year, engine and in the case of the X5 the type of AWD you have.

The right tools will save you lots of pain and suffering.

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X5 4.6 2002 Black Sap, Black interior. 2013 X5M Melbourne Red, Bamboo interior
Dallas