As Cab posted, we tried three differant carbs on the 416 but there was only 1 HP differance between them, not enough to worry about in my eyes. At the track I tryed a 950 hp and loss .5 in et from the 850 demon I ran. I also tried two carb spacers, 1" and 2". the 2" killed the et, dropped from 7.0 to 7.5, the 1" dropped it to 7.3. This is on a indy W2 intake with an 850 mighty demon....Phill