tornado and mpg
For what it's worth....the sceptical me, bought a "Tornado" air management device for my 454, a few months back. I was getting 6.5 - 7 mpg average at the time. I tried this only after hearing a lot of good comments on it, although some auto mechanics are more sceptical than I am. The unit mounts over your carb in the air cleaner, and makes incoming air swirl strongly as it enter the intake.
Well, after this a=was added, and a new set of park plugs, cap, etc. I got about 9mpg on my 2000 mile jaunt these past 2+ weeks. I can't say whether it was the Tornado alone, but I did notice considerably better "take off" on acceleration right after I installed it, and before the plugs were put in.