Thanx for the info Scott26.
Taking the info from the i8- 3 cyl motor, roughly double (6cyl) the hp would be in the 440 hp (330 kw) range. 100 hp more than the M2- as per Scott.
Reading between the lines- next m3- tri turbo, inline six, 330kw, lots of CFRP body parts- Sign me up!!!