First, and EFI intake and a carb intake have two entirely different needs. Trying to create an EFI intake using carb thinking usually doesn't equal a good intake. And EFI intake only has dry air to pass thru it, and is called a "dry" intake, while a carb intake has fuel/air mixed together and is much heavier than just the dry air in an EFI intake, and is considered a "wet" intake. The runner length tunes the intake to make its peak torque based on that determination. Read through the link of the article I posted early on to get an understanding of how it works. For a turbo 292, you will want the peak power to be around 4500 or 5000 RPM for a street engine probably, and a runner length of 15" to 16" will provide that. If you want peak power to be at 8000 or so, then a 10" to 11" runner will be what you want. In a nutshell, the Ramchargers formula for calculating the optimum runner length for a particular RPM is as follows:
84,000/N=L, where N is the desired RPM to tune for, L is the length in inches from the valve head to the opening of the ram tube, and 84,000 is a constant. Example below:
