I'm planning to go with Sachs shocks and the H&R lowering kit. Anyone have this combo? I already have the shocks, but haven't purchased the springs yet.

Coilovers are overkill, IMO, and the KW's are the only way to go. I have an e70 X5 M as well and I bought it with BC's installed- they are terrible. Absolutely awful. The problem is that they are not at all suited to the application. The rear springs, which are mounted inboard in place of the stock airbags are sized without any understanding of the motion ratio and are about 1/2 the required spring rate... This resulted in an extremely bouncy, crashy ride in the rear. I would think that you could upgrade to a stiffer spring, but you'd probably need to re-valve the shocks as well which doesn't seem cost effective for what is a very cheap, entry level damper to begin with. I just bought a set of KW V3 for the e70, but not going that route on the e53

e39_touring - I'd gone down a similar route but without changing springs up front or the lower air spring (bags) in the rear. I also am not trying to make an M car (I have one of those). I had a chance at B6 rear shocks (only on another E53 for six months) and replaced these first, VERY happy with the result.

I then upgraded the rear sway bar (my car had the 22 mm rear bar) to the larger diameter (23.5 mm) - this makes the car have more of an oversteer and flatter cornering. You can easily check which diameter you have with a dial caliper OR an open end wrench to check with size will and won't slip on the bar. Used bars are cheap on ebay, make certain you buy the type compatible with your rear suspension (coil vs. air springs) and suspension (std or sport).

Thanks, everyone! You've convinced me to hold on and wait for a set of Bilstein B6/HD's to be available. I've already waited a year and am not willing to pay ~$300 more a set to get them now vs my bavarian autosport backorder. I have a feeling they're slowly shipping the US again now.

I did fit a sport package-spec (23.5mm) rear sway bar as well because I had easy access to one. Honestly, I' m not sure I can tell its contribution because I did it at the same time as replacing LCA's and other bushings.

Stock X5s significantly understeer. You can reduce understeer modifying the entire front and rear suspension with quality aftermarket mods and tire and rim selection but it won't get to an oversteer condition.

You should get a award for patience.

With a sway bar that is stiff enough and shocks/struts that are in good condition you should certainly notice it corners flatter and turn-in is improved. However, sometimes positive results are reduced if the other components are not matched to the upgrades.

I used the Sachs sports for font and back and have been very pleased with them on the 4.6is.

Yep that’s what I currently run on my 4.6is. Very nice combination.

I was considering Sachs if the Bilsteins B6's don't become available again soon, but I see conflicting information on whether or not they spec a separate part for sport vs standard suspension. Their aftermarket catalog only lists 1 version for all E53. Most retailers note 'not for cars with sport suspension' while pelican parts shows different sachs struts for with vs without sport suspension - very confusing...

Bilstein B12 kit
 

I'm in a similar situation. I ordered the bilstein B12 kit (Bilstein 46-189523), which are the sport B8 version with matched eibach springs. I opted to go this route for better spring rate compliance with the valving and only a 30mm drop.

Here's the kicker.... I ordered them back in May. They were back ordered till Oct, now they are pushed out till Mid December! Whats going on over at Bilstein? Holy crap!

I have a set KW's, but I have opted to simplify things and will be passing those on soon. I mounted the rear springs to do a test, and the drop was lower than what I wanted. Soo.... I'm waiting like you.

Anyone here have the B12 kit? Any feedback? Thanks in advance.

I don't think that B12 kit actually exists. I've never seen a retailer with it in stock, and the photos always say 'coming soon' in the year and change I've been looking. Eibach doesn't even list the lowering springs for E53 on their site anymore.

The only place that lists B6 shocks/struts as in stock is ECS Tuning, but they are ~40% more than what I ordered them for at bavauto last black friday. Hmmm... maybe ECS will have a big black friday sale on them!