Highest flowing sbm heads?

fishmens67 said

2Hp cfm x 340 CI = 680 HP, like I said, Indy territory. 680 is good power, but I wouldn't say serious.

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I never got there on W2’s but I was close. I mad more than 2 HP/CID on W5’s but I had probably 100 hours or more in them. It was a PITA.