I have the SP3s.. they're better suited for a more aggressive setup. a search would have netted you this info, btw... but as mrfatbooty said in another thread..
They're like Koni Sports but they are shortened to help gain back suspension travel when lowered, they have valving designed to deal with lowering, and their spring perches have a 5-position height adjustment instead of the normal 3.
except that i think the regular yellows have 2 spring perch settings on the rear, not 3 (if i remember correctly).
in other words, yellow SP3 > yellow.