Wouldn't the Volumn of the Air Box and Total Intake Cam Timing DEGREES per Cylinder determend and with 2 Scoops feeding Box you have to have enough Volumn to Feed Cubic Inchs + VE ?? 420* + 315* are just Odd Timing, just Need ENOUGH Volumn to feed Total Cubics Inchs, as 4's with 180* , v8's @ 90*, v10 @ 72", v12 's @ 62*, v16' @ 45*. It is about ENOUGH Volumn of Air Box vs Cubic Inchs per Cilinder