Done a couple of blow through setups and a very small carb seems to work better. I did a blow through BBC with 2 450 Holleys in a box. Made 960hp at 5600 and 9psi on a 502 boat with iron heads. People I talked to said the smaller carbs would run better than even 600s. I didn't argue, but the customer was very pleased. I did a 250 blow through in a 62 Chevy II and got the best results with a Ford Autolite 2barrel from a Ford truck. I still have it and will look for numbers if you want. You can get them for cheap and they are bulletproof. Turbo makes the air denser, not faster so a carb big enough to run your engine NA will run it just fine with boost Also, annular boosters work best. You might check on The Turbo Forums for blow through carb info-they have a lot of great info on this!!!