Every thread seems to be a thread turning into a "bash the M4 badge name" thread, come on guys.
The lack of power increase has been speculated for a while, but it's still just that - speculation. I personally won't believe anything until BMW announces it.
And so many people are worried about power, why? Turbo powered cars are so easy to tune and get power out of. I can't imagine it'll cost more than 4-5 grand to up the power to 500 bhp or so.