I would go with the stage 3's, that and the TB gave me 27rwhp, i would think the stage 2's would be more like around 15rwhp and stage 1 probably not that much. I would change out the springs for any cam swap, since your in there, might as well. I know brenspeed will only sell stage 3's and said stage 1 or 2 isn't worth the money or time.
Stage 3's are definitely streetable, you wouldn't no if i had cams or not. I feel a little lump here and there, barely.
2014 Mustang GT, A6, Grabber Blue