I have bilstien HD's on my car, and they were a cartridge insert. Just as bitchy to put in as any strut insert would be, but well worth it. I reccomend getting them, and having someone install them. I'm still trying to work all the bugs out of my own installation; when you get them put in professionally, at least you'll have someone to come back to if anything goes wrong. The only way you can tell if a car is sporting front bilstiens is by looking at the size of the strut piston shaft. It's about twice the size as any of the others, including boge, KYB and koni. HTH! -alan 83 320i 79 320i