Yes. A little more peak HP, but much more at lower RPMs. I all know is that with the tuning I recommended above it made a HUGE difference. Although I did not dyno or run it right after, I'm sure I would have picked up another .2-.3 in the 1/4 easy. Throttle response was immediate and there was no more lag into the secondaries. The tuning is free, and you can pick up the sec. metering rods from any GM dealer for around $20 for the pair. $20 and 30 minutes of your time is well worth the effort. And just maybe you'll forget about changing over the carb. The GM part number for the rods you want is 17053659.

I'm sure Damon might chime in. He has had some success with QJets. He is the one that helped me out several years ago.

 

All computer controlled QJets were 750 CFM (capable, at least, once the secondary air valve was allowed to open a full 85-90*), as far as I know.

The difference between a 750 and an 800 CFM Qjet is in the PRIMARY bore size. The 800s had a primary venturi diameter about 3/32" larger than the 750 CFM units.

How to tell which one you've got:

750 CFM: Look at the primary venturi (NOT the booster venturi out on the "stem") cast into the main body of the carb. It will be a perfect concentric circle all the way around.

800 CFM: There will be a pronounced "lump" on one side of each primary venturi.

Computer controlled QJets don't have the "lump." I just went and checked on several that I have in my collection and none have the tell-tale 800 CFM "lump."

 

Ok.. well I am only 16.. so this doesn't exactly make the most sense.. lol..
Matt