Yeah u will need to change out your injectors.
Also if u plan to switch maps, accessport is the easiest way to do it, and easily mobile(not having to lug a laptop around)
Also, u will be fine running large injectors on 91 as long as its no cheapy company. Go with a good well known brand. they just need to be scaled correctly. And yes u will pass smog with larger injectors as long as they are scaled good n your tune is good.