Effects of bronzer/Venturi and were They end

wondering about bronzer/Venturi board and were the end of the concave should be or is. I have noticed some boards have these concaves almost running out the tail others have them running out from just below the front fins a bit. I would think the concaves running out the tail would have more drive/speed and the concaves running out just behind the front fins would be looser and maybe turn quicker. Can someone who knows more about it let me know thanks