^^^^ THIS ^^^^. Not specifically fuel supply, but the law of a chains weakest link. ie: If your fuel supplies limits your combo to 10.80, and you make improvements elsewhere, even if they were effective improvements in their area, the limits of your combo will most likely still be 10.80 because of the fuel supply system. Now weight improvements would seem to be the exception to this because less weight should ALWAYS be faster, but it still doesn't always seem to work. I know what I'm describing seems to be just stating the obvious, but think most of us still tend to ignore the law of the weakest link. I know I do.

It would seem to me that key to making effective changes is to continuously know WHERE your weakest link is. And that's not always easy! Again, obvious.... right?

To the OP: I made the move from steelies to lighter rims on my car and saw about a tenth improvement, but I changed tires and gearing at the same time, so....