My brother just got his engine all together today. 426 with 13:1 compression, Hot Cams stage 2 cam, and a heavy duty rod along with a White Bros high rev CDI box. He ordered a 39mm carb and a Curtis Sparks X-6 exhaust for it, but they aren't here yet. So, right now he is running the stock carburetor, a DG slip on and the crappy stock headpipe. This thing is crazy now. I didn't ride it much, but at just over half-throttle it's already running harder than the stock 400, wide open (with full DG exhaust on it). The 426 isn't even fully broken in yet. He just put in the race gas a few minutes ago because the initial break-in is done. As soon as the carb and exhaust system come in, this thing is going to friggin scream!