If you're serious about air flow you might want to look at this. http://blp.com/ The 1.405 venturi billet main body will flow 1020 cfm and still have great throttle response.

The the XP-950 Ultra shares almost nothing with the HP950. Different metering blocks, fuel bowls, body, all different, I think even the base is different. The throttle bores are 1.75" and the venturi diameter is 1.60. A standard HP 950 i believe has a 1.37" venturi with a 1.75" throttle bore, substantially smaller.

What do they flow mike? I haven't had one in hand nor need for one yet but will likely in the future.

That's a riot carb swapping between pulls and comparing btw.

Does norm still work his magic for customers. I would imagine he's not cheap however either are new carbs that don't compare. You know what I'm saying. I've got four practically new 850's and after all was said and done I had planned to replace with 4150/1050's.

Std Holley 850 is 1.562/1.75
I still like the 950hp's given the right build. Although holley trick fked many before the measuring started they still had a nice carb yet brought a lot of light to what was going on in the carb business. Been many improvements since. Some nice stuff out there now a days.

Yes, he relocated from tuscon arizona to vassar mi and built a carb shop at his new house, still does them, guys a wealth of knowledge. There are sections in the holley book that refer to him, numerous car craft , phr and hot rod articles back in the 80s and 90s where he did dyno testing, carb setups for articles, testing and articles david vizard did that used his dyno and carbs (same dyno thats now in my shop) there is a certain 850 holley he prefers to use as a starting point for his highly modified 4150, he's still experimenting with new mods too, he's doing a oval mono blsde on secondarys on one of his newest experiments, does a split fuel carb with e85 or methanol on secondary sides, any questions on having custom carbs built here is his website w contact info:
http://www.compfuelsystems.com/

Yup.
Holley Ultra 950 that has a 1.600 venturi and a 1.750 throttle bore

Furthermore, I did some digging on the Bullet for the Holley's and QuickFuel literature for their carbs

- 750 and 750HP CFM 1.375" venturi x 1.6875" throttle bore
- 830 CFM 1.562" venturi x 1.6875" throttle bore
- 850 CFM 1.562" venturi x 1.75" throttle bore
- 950HP CFM 1.375" venturi x 1.75" throttle bore
- 1000HP CFM 1.562" venturi x 1.75" throttle bore

Quick Fuel
M-650 1.312” venturi, 1.6875" throttle bore
M-750 1.375” venturi, 1.6875" throttle bore
M-800 1.312” / 1.437” venturi, 1.6875" throttle bore
M-850 1.560” venturi, 1.75" throttle bore
M-850-B2 1.560” venturi, 1.75" throttle bore
4150 1050 1.590 venturi 1.75" throttle bore
M-4710 4500 1050 1.710" venturi 2.0" throttle bore

I'm not sure what they flow. I know when I was deciding on what carbs to buy, the XP-950 was really high on my list. Somewhere I found a guy that compared the XP to a Quick Fuel 1050. Both flowed around the same, but the Quick Fuel had a better signal. All the research I've done over the past few months, Quick Fuels will flow their number or slightly better. The main reason I decided to to go the Quick Fuel route is if I need to, I can just swap out the main body and have a 1050, you can't do that with the Ultra's because Holley isn't selling Ultra bodies yet.

I remember talking with him a few years back now that I think of it. I'm going to give him a shout regarding my current 850's and as soon as I can afford it I'm going to run them over to him. Just have a lot of unexpected chit on my plate right now. Nice thing with norm is he will likely have carbs near bolt on ready with very little tuning for my specific builds.