I'll probably be watching this thread, cause Im thinking of a Demon too. I run a Holley 3310 now, and it's good, no problems. But Im building a 496 that hopefully will be done in about a month, and I want to go a little bigger.. Im thinking of a Demon 850, but vacuum secondaries...I ran two different double pumpers, and found that switching to vacuum secon. helped my performance quite noticeably. Of course, you no longer will have the 'bragging rights" of the mechanical carbs, but once you get over that part, it's really about the performance, right? I know a couple guys who drag race, and they made the same change, and saw either no change, or actually picked up a little on the ET. That was enough to make a believer out of me. But anyway, I like the looks of the Barry Grant carbs..Nothing wrong with Holley, I just want a change. John