I used to notice a puff of white smoke in 2nd gear in my old 2008 MPS and have also noticed this a couple of times in my new Gen 2 with only 2000kms on the clock.
It usually happens when the revs get over 5000 rpm in 2nd gear just before gear change when giving it a bit of schtick. I never red line it but open it up every now and then.
I mentioned it once about the old car to Mazda when it was in for a service but they claim they couldn't see it. I've had no other issues with either car and it makes me wonder if it's just the fuel being burnt fast!
Comments much appreciated.