Just my opinion - I looked dove deep into springs and shock years ago and there seems to be three tiers of aftermarket performance coil-overs.
1. The bespoke race prepared that have the highest level of engineering and quality control, i.e. Penske, where the design (using sophisticated requirements) matches the final product proved by data charts.
2. The street performance / track day that had someone at one time copy a design or make a good guess at design inputs and try and deliver that as a consistent product, i.e. cataloged part that may or may not have a data chart for proof that it is as designed.
3. The street "performance" that are cheap and fit AND really look good and probably work good enough for the street.
As I tuned my Europa's suspension on a track and tried stock, Koni, AVO, and Protech shocks with various spring rates and calcs, I have tried to leverage group #2 with some attributes of group #1. I could only do this by personally speaking to Richard Winter and Barry Spencer who both road race Europas. That way I could use their experience and request a certain spring rate with a certain dampening. With our choices in the market, I still don't have the shock dyno graph I would like, but I trusted that these two gentleman had at one time validated the result.
My issue with the worksheet shown is that it not only uses a Lotus 7 for the input, but does not mention the type of driving, the spring rate, or anything about damping. As a automotive aftermarket manufacturer, I recognize this as a build sheet for an assembler. Too bad they couldn't have a Customer Requirements Sheet. This puts that shock in the category of #3 for me.
