Ok thanks, that makes sense about the part numbers. However, I am still not convinced about the quickness/tightness issue, and have to disagree with you there. Whenever I drive a ZHP, it feels like there is something about the "rack" itself. I know exactly what to expect from control arms, from shocks, etc. None of them add up to the steering feel of the beast :dunno:
I have also driven 02+ cars, that's I meant with "having owned/
driven both".
Looks like you remember me just fine. Then you might also remember me participating in those discussions about the rack. I gave a break for a couple of years, and I'll give it to you, you guys look like you have made some progress about the part numbers, and what they mean.
What is still baffling to me is the steering feel of the ZHP. As I said above, the way I feel when I drive a ZHP forces me to isolate the feel as if it's the rack itself.
So I'm after what exactly is different on a ZHP rack. jpr at one point said it may be about its internal tolerances being tighter. Along these lines, I think it is very plausible that the M-Pack II internals might be the case here, as it does have specific part number for its rack.
And there is no research that has been done on this front, so I'd appreciate if you have something to post other than "part numbers", etc. Here's a thread that came very close to solving the mystery (which I have also participated back in 2008):
http://www.bimmerfest.com/forums/showthread.php?t=283973. People there talk about retro-fit kits, etc.