1) They are a lot stiffer than any kind of OEM-style shock/strut (duh!). They do not have click stops like Illuminas or other street "performance" shock/struts, you just twist the adjuster to the stiffness you think you need. Not having any kind of reference, I put in a full twist of firmness on the rears and a twist and a half for the fronts. The short test run around the neighborhood felt OK and so I took a 30 mile run down the LA freeways as an extended test. Oooohhhh Boooooy those baby are stiff! Like almost no movement in the suspension stiff. Too stiff for lousy LA freeway pavement stiff. Shake the fillings out of your teeth stiff. This can not go on stiff.
I backed way off on the stiffness and ran another 30 miles back home and that was a LOT better. I am looking forward to getting the car on a smooth track for more testing and tuning. For street driving... well, these shocks are not well suited for street driving, but if I do drive this car on the streets I will back the firmness even more.
2) Konis make all the imperfections in your suspension come to light. Minor problems in alignment are brought forward, front and center. Is your alignment was off by a smidge? You will discover that it is WAY off with Konis. Corner weights not close? You will be begging to get your car on the scales once the Konis are on.
3) If you have a loose rattle before you now have a symphony of parts calling out to you now.
As I have learned from first hand observation: There is a world difference between "performance" parts and real racing parts.