Highest flowing sbm heads?

Ultimately I'm not trying to pick a fight or anything. I respect what work people have done and most of you have done more than me, I'm just trying to learn and think about what is next for my next build. I would just like to know what heads out there are capable of say 350 cfm or more. Either they exist or they don't. It's not meant as an insult to anyone. This stuff does exist for SBC btw.