Carburetors,3200 lb.412 sbc.2010 350 trans foot brake,Profrom modifed 750 9.67 140.14 best.Pro systems 1000 Holley hp 9.70 140.63 best.2011 same motor glide trans brake,same day test,Proform 750 9.62 140.80,Pro slstems 950 holley hp 9.70 140.71.Same track good air Proform 750 9.55 142.14. 2 weeks later good air Holley Ultra aluminum 850 9.38 144.93.The new aluminum holley did the best for me.Bill.