lee,
What size engine and rpm range do you have? How much boost?
I do remember throwing up a chart for picking a turbo. I have books and calculations for use with figuring the boosted flow.
Keep this in mind. If a 600 cfm Holley works good on a N/A motor, it will also work good in a boosted application for the same motor if it is blown thru. Of course the carb will need modifications to handle the boost, but that is a different story.
The boost makes the carb feel or flow bigger. So a 600 cfm will flow 750 cfm at the right boost. Tom
