Is it too late to contact prospective PI's at grad schools I applied to? I applied to several grad schools and have heard back from two - rejected (somewhat expected) and waitlisted. I had other things going on and (stupidly) did not contact prospective PI's at the other two schools (well I contacted one and received a form response and thought maybe I should just wait to hear back from schools before talking to more prospective PI's).

Is it too late to contact prospective PI's? Most admissions committees have already started going though applicants and setting up interviews so at this point I'm not even sure what I'd say. If I had emailed when I should have (before applying), I would have said I was thinking about applying to that university and was interested in their work then asked what projects a new graduate student might work on.
I think contacting Profs is only helpful if you are genuinely interested in their works and have good questions to ask. If you are contacting Professor because you think they can help your application get accepted, it might not help at all. Profs are smart, they can easily recognize that.