I dont know how a rear diffuser would look because of the two tone, not sure if having black body, then a lighter lower body, then going back to the darker black diffuser would look, same for the front lip. I would first get a sport grille before anything. I personally like the 09 wrx grille better then the sport grille. Any idea whether you can take off the wrx emblem on the 09 wrx stock grille? I would also get the chrome rear insert done along with the sti spoiler as well before any front lip/rear diffuser. At least with those you can get a perfect match whereas doing lower body work might not look good because of the lighter color on the lower body.