A question about A-Fuel vs Blown

Hey guys, I'm not as up to speed on the Alky Dragsters or FC's for that matter as I'd like to be. But do the alky dragsters go by a Weight per Cubic inch formula? Or just Maximum Engine size and Min. Weight? Do both Combo's have the same weight break?

 

Non-supercharged single engine,nitromethane: 4.80 pounds per cubic inch weight break; maximum displacement 470 cubic inches; 2,025 pounds minimum weight.

Supercharged, single engine with Roots type supercharger, methanol: maximum displacement 528 cubic inches, minimum weight 1,950 pounds.

Supercharged, single engine, with screw type supercharger, methanol: maximum displacement 466 cubic inches; minimum weight 2,025 pounds. Competitors may continue to use larger engines by adding 5 pounds per each additional cubic inch to the stated minimum weight.

 

That's Nic, I don't understand why they have Cube limits if it's based on weight per cubic inch! If someone wants to run a larger motor, is that an advantage if they have to add 80-120 lbs.?