Engineering Transfer, Old Scores question

Colleges and Universities A-Z University of Pennsylvania
1

So I’m planning to apply as a junior transfer to Mechanical Engineering for fall 2016. I know that we have to send our high school transcripts and SAT scores. Unfortunately, I did very poorly in high school and basically screwed myself over but turned my life around in college. I probably graduated with like a 3.0 and had like 1600 SAT (1140 m/cr).

  1. Are these poor scores going to affect if I'm admitted or not?
  2. If not, why do they even want these scores?
  3. If they do matter, should I retake the SATs? [can you even retake them as a college student?]

Also, what’s a good gpa (or average admitted) to be competitive to transfer to Upenn?