I have no problems accepting the ratios being the same, or the part being the same for that matter. However, my experience, after driving both 02+ cars and ZHPs, is that there is a difference that I cannot associate the feel with the arms or shocks or any other suspension component up front. I have replaced shocks, arms, sway bars, etc. on the BMWs that I have owned, and I think I know exactly what to expect from each one individually. I also replaced the steering box on my wife's older 5er touring, and my expectation before and the feel after the install matched perfectly.
I would love to hear from a non-ZHP owner about the steering feel who had the ZHP arms and shocks installed on their car. Can't believe nobody did these mods...
As I said, the rack can be the same (thus no confusion at the factory), but there have been discussions about additional hydraulic lines and/or retrofit kits when people were having racks installed on their ZHPs. Any comments about those? I'd love to hear more. Maybe there is still some unexplored territory here.
Last edited by SeanC; 09-24-2012 at 03:13 PM.