The changes on the Sigma 2 over the current car ,that i can tell are :
new front and rear susp. arms(slight redesign ??)
new front and rear hub carrier's that will use smaller bearing's
new steering arms(knuckles)
new front and rear shock towers (slight redesign)
front and rear upper tie-rods mount to the shock towers instead
of the bulkheads
front and rear sway bars mount from the front and rear of the
chassie instead of off the top plate
there maybe other changes annouced as more details come but that what i can see for now!
Kawada must think these changes will make a already great chassie even better!!