how much shorter are race koni spss3, compared to normal koni yellows?

1" shorter off the shaft and body? so total 2" of the whole shock

 

Fronts are 25mm shorter, rears are 15mm(?) shorter. Not sure on the droop limiter change, though I can't imagine longer droop limiters being used. Most of us don't care about droop limiter length as the rates we run are so stiff the shock has more droop range then the spring does. For your car, you might want to give Koni a ring and find out. Topping a shock out is as bad for grip as bottoming the shock out.

 

front body 25mm shorter, 40mm more droop

rear body 15mm shorter, 35mm more droop

all of this avalaible on koni website