the main issues I've had with edelbrocks is calibration. I don't understand the reasoning they've come up with here but I suspect they're catering to the small block chevy crowd. anyhow, once that has been overcome these carbs are very reliable. I think the real downside to them from an all out race standpoint vs holley is the internal fuel passages size. I run a pair of 600's on a ch28 intake and really like this system. tweaks to the carbs were minor but in the end the best intake system I've run on a 440. a friend has an 800 avs on a 427 chevy and that thing took some radical changes to straighten out, but the end results were surprisingly good. I think the 650avs2 I a good step forward for the smaller engines. it's all about the cruise mode. I've found any off idle transition issues to be more related to idle af/ratio and too large squirter.