haha, Mazda

Yes, in general hi-swirl is best for mid-range but not for high-rpm power. Remember how the original Chrysler hemi had awesome power but poor part-throttle response. The new hemi is high-swirl.

* The newest A12 head (G61) has combustion chamber like the H95 but with regular round ports.

* The previous H99 A14/A15 round port had a hi-swirl chamber design instead of hi-swirl port design.

All three are good mid-range heads. For people that prefer not to "rev to 6,000 rpm"

G61