Which Is Correct: "Do More Faster" or "Do More, Faster"?

"Do More Faster" (no comma), because it provides no break or breathing-space, successfully suggests the speediness that the book is trying to promote.

"Do More Faster" confuses two grammatical roles of "more." The book's author intends it to mean "More (Things/Projects/Work/etc.)," and you can see that the comma wouldn't be necessary if the noun were included thus: "Do More Work Faster." Written without the comma, however, it makes "More" seem as if it modifies "Faster," and that would be grammatically incorrect. ("More faster" is certainly unacceptable.)

Therefore, "Do More, Faster," would be my preference for clarity, but if we accept the author's intention in using "More" as a noun, the comma becomes unnecessary. (And I agree with Martha's point about this usage being a title; in that context, the comma's absence is more acceptable.)

Both are correct, and while I can see where you're coming from with the meaning distinction you make, I think the intended meaning of both is the same (i.e. both "more" and "faster" apply to "do"). The version with a comma is somewhat more clear, but I can totally see omitting the comma in a title.