I went to a top-tier undergrad (consistently top 5 in US News colleges), and I did a research project under supervision of a grad student my junior year. He went from your-average-joe U to this place, and he was even more impressive for it. His prof (who also ran the project) told me that his recommenders said he was easily their best student in 15 years. Having said that, the grad student did admit to me that a class that we were both taking was a big time wake up call for him, and he'd never seen anything nearly as hard before. I came away very impressed with him for making it to this school and also taking on a big challenge in a classy way (I think he ultimately did very well).