Well...I'll take a stab at this.
The Cheetah vs. the cubs are more than just power valves.
They are different intakes as well, which are CR500 style I believe, which will flow more...
For drag racing, the powervalves will not matter... the bigger cheetahs have the powervalves blocked off anyways.
However, the cubs are less expensive and stock components will fit..intakes, head, etc....