@gdlbmw, my X is super low, but i have a 4.8is and air.

General rule of thumb i follow though for cars i do suspensions on, and the like,,

Matters even more if your up there in mileage but i just follow it regardless,

If your going to lower the front, replace the struts as well, and doing the links in the rear, you might as well do the shocks (not called struts in rear).

Given, most of the cars i do have springs in all four corners, but matching struts/shocks/coils will work for you for the better (this is why coilovers always work better then having to match springs/shocks/struts all seperatly by yourself, some cars there is also limited aftermarket, meaning, ok H&R offers lowering springs, but you cannot find a better matched strut/shock combo for them, because all thats offered is OE spec replacements) .

And once again if your up there in miles, and going to be taking all of this apart, another thing i do is, why take it apart 20 times, when im doing a susp refresh on a car around 100k for example (recently did my fathers), i replace the balljoints, bushings, tierods, stabilzier links and bushings, etc, as well as the struts/shocks/springs, i put H&R lowering ones in as he wanted, just for the record but yeah.

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2006 X5 4.8is Fully Loaded