I've read this thread a few times trying to figure out just what the hell mandoble is trying to say.
I went on-line and ran this test with a 190A-5. I took it to 5000 feet and leveled. I accelerated to 275 IAS and then dove to the deck where I acheived around 450 IAS then leveled off below 100 feet. I let the speed settle and took a snapshot.
With a full tank of gas:

And with a quarter tank of gas:

There really wasn't much difference, with the slight edge going to the plane with less fuel (the lighter plane).
Then it occured to me... mandoble is probably refering to acceleration. That's when I really started to laugh.
Mandoble... does it take more work to move something that weighs 1000 lbs vs something that weighs 10 lbs? Do you know what horsepower is a measure of?
AKDejaVu