Several things to consider.
Eibach does not make springs for XI's, so what you are using is for non XI model (hopefully for the 328). The drop Eibach specs for pro kit is for non XI's. OEM XI springs are much stiffer than non XI, and Eibachs are about same overall spring rate as OEM non XI, just lower ride height.
For non-XI, non-ZSP sedan pro kit drop is 1.4 front and 1.0 rear, ZSP sedan or coupe is 1 front and .8 rear. But none of this matters because you have an XI with much stiffer springs, higher initial ride height, and a heavier car. You are replacing those springs with much softer ones that already give 1.4" drop on a lighter car using the SAME spring rate as the non XI car. Unlike the coupe vs non ZSP sedan on non XI, XI has no OEM sport suspension.
So point is drop should be more like over 1.5" on an XI in front, if you had only done springs. This is why me and others are scratching our heads. If it settles out that is great. Sometimes mcP strut front Bilsteins trap air in the bottom of the strut housing under the "rod" (which is actually the shock body), and this air farts out over time lowering the car.
Time will tell. Right now you have an interesting combo of stiff OEM XI rear springs and soft fronts, but the unusual ride height going on. Lot of folks (including me) who put on the full pro kit F&R found the rear too low WRT front, mainly due to weight issues and softness of rears. I put on a set of OEM D2 ZSP rear springs and that equalized the fender gap F&R to about 1-1.5 fingers. Before the rear looked too low which is the rake everyone talks about. No rake now. Have Koni sports as shocks, 335 e92.
Anyway I think your plan is good drive around see if it settles. Springs do not settle but rubber parts like spring pads, maybe new strut top hats, and excess trapped air does. The Bilsteins are high pressure gas monotubes so you will have some offset force due to internal pressure from inside the high pressure gas chamber in the shock body itself (this is what everyone talks about with higher ride height, not the trapped air under the strut housing) but that should only be 1/4" tops.
Many people are not pleased with the lowering perches, I'd read up on them before you try them. I am opposed mainly because they reduce travel, and lowering an XI w/o coil overs already reduces front travel considerably.
Last edited by ajsalida; 05-15-2014 at 06:25 PM.