I LOVE threads like these~ Good info. That sounds like it's within my ballpark of fortune. This is my goal for my LS1 as well, twin turbo's. This guy has a site dedicated to his twin turbo 2nd gen that I found many years ago when I first came here. Hope it MIGHT help if at all. He has MANY PDF files explaining CFM, turbo selection, etc etc.....it's a MUST IMO for a 2nd genner Turbo enthusiast newb like me. Grape Ape http://www.grapeaperacing.com/ Yep.....I didn't know this either until I did some looking into it. Take a 2008 Saturn Sky MPG vs a 2008 Saturn Sky Redline (turbo) MPG and compare.... The turbo gets the same if not 1mpg MORE.......as long as you keep your foot out of it.