My motor is a BBC 468, single 1050, around 750hp in a Canyon flat. 106 at 10:02 is the best at the races. Was running Basset (dry) headers and had the chance to test with some Rewarder zoomies today at the lake. Since my last test session with headers the only change was the weather , today about 80-85 degrees, last time about 95-100. Jetting (92), gears (12%), prop all the same. With the zoomies the motor wanted to idle much higher (about 1900 initially ), my idle with headers is normally around 1400. She was a dog compared to before with the Headers. Real bog when I hit the throttle under load. Did some idle mixture adjustments and the idle increased to 2500rpm's, sounded better,improved some performance, but really lost about 600 rpm's on the burnout (6100 down from 6700). Zoomies lose that much power in a carbureted set up??