As far as I know the car has one, I think 16mm. The 19mm is the WRX stock one. I dont know if the 16 bushings will fit the 19 & I think u can just use the endlinks that are there.
One way is to just look under the back of ur car. U will just see a bar going from one side to the other.
I haven't done this yet. Its either that or strut bars.