Originally Posted by MassiveMods

the main difference between Turbo and Standard button is the Geometric compression ratio. Turbo heads have a larger roundish dish. this has several effects

Hi all i have to edit my info , ive been corrected on the information, it was my impression that refraction is influenced by the shape of the dome.. its not so , what a larger dome does is allow for a larger charge to occour which is evenly transferred to the piston regardless of the shape ..

Woo hoo !