Glen,

Its interesting that the 500 shocks work well on the 320. I installed sportline shocks on my 320 and am highly disatisfied with the results. Steering feel has declined significantly; During the compression cycle of shock travel, it feels as if the shock is bring the vehicle's downward motion to an abrupt halt (springs still moving), which suggests that the shocks are too short for stock springs. In the other words, the car feels very spongy. This appears to be consistent with the fact that Bilstein sports are for shorter springs and HDs for stock springs, while both provide similar damping characteristics.
Now given that 500 springs are shorter than 320 stock springs, I would postulate that one might observe similar behaviour to what I described, if one used 500 shocks in a stock 320. Apparently not? :-)
What are your thoughts?

farrukh