I just went through a big deal with carb sizes and tunning on my BBF 429. I started with 2 600 vac sec Holleys that ran perfect but only pulled the motor to 5K rpms, and did not have much top end or mid range. SO I called the pump master MPD and said why? He said he runs 2 750 dp Holleys on everything, so I took his advice and Whamm just like that it was a new boat!!! 5500 rpm's and a best of 76 mph on the Gps( No diverter or droop yet). I barley touched the carbs, I just adjusted the float levels and jetted it down a couple of sizes and ran PERFECT ever since! Don't sell out short go with the 750 dp's!!!! Just my experience!!