I thought the front eibach bar was discontinued? I think whiteline makes a f&r set.

You are correct, have to find it on Ebay or otherwise.

Like this guy right here with two sets. Eibach Sway bar Anti Roll Kit for BMW X5 BME40200090111 Performance Stabilizer K | eBay

I hadn't realized this previously, but these bars only list compatibility on the pre-facelift models. 4.6is is covered, not the 4.8. Anyone know if that's a real limitation or just documentation?

Yes Whiteline does make a front and rear set but its is discontinued and they sold off the remaining few they had in in stock at a substantial discount. I paid $54 for the rear and $78 for the front one on closeout from the manufacturer. Last time I checked I think there were a couple of the rear sway bars available.

Damn that is a deal! I would have swooped them up at that price too.

I noticed that too.
I've also read that installing the rear Sport (23.5mm) sway bar is a nice upgrade from the non-sport (22mm) sway bar. I'm surprised 1.5mm actually makes a difference honestly, but...I'll ahve to trust others. and those can be had easily at $100 or less on ebay

That 1.5 mm is more than a 14% increase in the cross section of the bar so the extra stiffness ;) would definitely be noticeable.

2002 X5 3.0 313,700 miles
2014 428i 23,700 miles

2004 325i sold at 123,600 miles
2001 325i sold at 66,000 miles

1970 Firebird - Under restoration

I think Ultra Racing also makes a set of these for the E53... as well as underbody chassis stiffening bars. I've used one of their upper strut mount bars on an 11 Optima SX... it made a difference.

No experience with their E53 stuff though.

thanks for tihs, but I have to say I've read on a few sites selling the Eibach bars that they are only for 2000-2003 model years for some reason. So I'm more open to buying a rear only sway bar, and even though the EiBachs are much thicher than the BMW OE Sport model, the 23.5mm sport version bar is much cheaper and worth trying first, foe me. I really enjoy how the factory suspension set-up drives. I dont want to change it too much.