Usage of ぼく and 私
 

I know that most HS boys would be using ぼく when speaking to other people, but what about writing? What would they use then?

Will they ever use 私？

You need to understand that the usage of these pronouns has less to do with your gender and more to do with your social status (which includes gender, but is not eclipsed by it) and target audience.

It's like saying "teen boys say 'sup dude' but does this mean they write that, or do they write 'greetings'?"

It depends on what they're writing, and to whom!

I agree, who you are talking to has/should have the biggest influence on how you talk.

Contrary to what seems to be the popular belief, it seldom depends on who you are talking to as far as HS boys and their use of 私　are concerned.

In high schools, オレ is by far　the most used 1st-person pronoun among the male students. When they talk to teachers, they use ぼく.

In writings such as compos and reports, most use ぼく. Very few use 私 in either speaking or writing. I went to a HS with about 600 boys and only a handful used 私 in any situation. That was like less than 1% of the boys.

I can't imagine a high school boy ever using 私- they want to look cool, so they use 俺 unless speaking to teachers or other adults who wouldn't approve of hearing them use 俺. I also don't think I have even once heard my husband use 私- it's either 俺 or ぼく.

That was what I was looking for, thanks!