I got an O2 sensor and found the thing to be relatively useless... at least when i first installed it. Maybe i need to try again now that its broken in a bit i guess.
Edelbrock carbs are essentially a copy of the Carter carbs, much in the same way the Demon carbs are copies of Holleys, but I guess without all the fancy "scientific" advancements that Barry Grant likes to promote. Essentially Edelbrock started with a Carter carb and added some slight differences/modifications to them to make them better, I guess like Demon adding 4 corner idle adjustment essentially to Holleys 2 corner carbs.
The thing I've heard the most is essentially that Edelbrocks are easy to dial-in and that you can easily get the most out of the carb. On the otherhand, a Holley is harder to dial-in, but the performance potential is greater... essentially if you can dial-in the carb perfectly you can expect more from it, but its harder to dial-in.
In hind sight, I kinda wish I had gone with an Edelbrock. I went with a Street Avenger 675. The Holleys are hard to dial in and most of the time i feel like im dealing with witch craft trying to guess at which tuning is the best for the carburetor. I've read books about how to dial in carburetors and they say run the thing at full throttle and shut it down (with the throttle wide open) to check the plugs to see the mixture at full throttle. Problem is, I cant do that in my neighborhood and I read on Edelbrock's website that plug reading is becoming obsolete because additives in gasoline get rid of the tell-tail colors we are accustomed to seeing on plugs... go figure. Lastly, changing the aerration valves and springs (or whatever theyre called) on Edelbrocks has to be a lot easier than changing jets/power valves.
In closing, I would say people's luck by switching one carb for another and having the car run better is simply that... luck. From all the reading/investigation I've done into carb tuning, a carb cant be tuned perfectly for every application, much less two similar applications. Seems almost every engine needs a different tuning. Multiple emails to Holley for tuning suggestions (and receiving several contradictory responses) seems to verify this.
Hope this is of some help