Just as a reference, because I think a lot of people with teen appropriate comics in this thread are saying they have 17+ level comics, the official guidelines for movies are:
PG-13- swearing, violence, some sex. A standard action comic should fall under this umbrella.
R (under 17 not admitted)- heavy swearing (this would be like an F bomb as a verb rather than as a curse), heavy sexual content, heavy violence (think splatter gore) and explicit and prolonged drug use.
Think the difference between James Bond and Kill Bill-- I think a lot of people in this thread are saying they want 17+ readers because they're 17+ but violence is (legally) totally appropriate for the kiddos! So is mild sex! (which is the Tap rule anyways)
The only reason I consider my comics for older teens is bc the extensive drug use with explicit rendering (it's not implied, it happens) but I reaaaally don't think anime-style violence is 'adults only' at all.