Boyan,
If you plan on applying for Endo right out of school, you pretty much have to be cream of the crop to have a chance. Board scores have to be AT LEAST safely in the 90's, and your class rank should be at the very top. If you don't fall into this category, you will probably need to do a GPR and have some private practice experience under your belt. Most programs look for experience, and there are a good number that won't even consider you if you are still in D-school. But that isn't necessarily a bad thing. What you know and think about Endo are going to change drastically between you first 15 cases, and your next 80. There are exceptions, but more likely than not ,only after you've done a good deal of Endo are you going to feel ready to tackle all the advanced cases that a post-grad program is going to throw at you.
Even with experience, Endo is still very competitive. Doing research and getting published can help out a great deal. Just keep your grades up and try to maintain you academic standing. Ultimately, academics are still the number one criteria for any specialty program. One more thing. Endo doesn't participate in the match. Applications and acceptances are on an individual basis.
bc