MSTP is super-competitive and the peer group that applies for these positions will have super-high GPA's and definitely MCAT scores. Often times connections among researchers can help but usually won't override for an applicant with a lower GPA for MSTP. That said, you should look anyway at whether any schools you are applying to have strong research programs. There are lots of opportunities to do research regardless of where you go to medical school, and that diversity of institution among those research programs could play in your favor provided you are doing well in medical school.