What all you guys are describing is part throttle detonation exactly like I had.
I'm from the mazda 6 club forums, but I had to come here and let you guys know about the fuel pump TSB: http://www.o-m-g-w-t-f.com/stuff/Mazdaspeed6/01-022-08-1919b%5B1%5D.pdf
This TSB has fixed both the...