Small beer yeast question

I'm doing an Arrogant Bastard clone today, and thinking of making a small beer out of the leftovers. I plan on getting about 3 gallons out of the second beer, and I have a Cooper's Dry Brewing Yeast for the second batch. Should I pitch the whole pack or would that be overkill?

Well, I ended up with just under 2 gallons in the bucket at 1.054. Rehydrated the yeast in a cup of warm water and threw a little over a half cup in.

Well you can never over pitch a beer so I would have used the whole thing.

It is possible to over pitch, a topic which has been discussed at length on the forums. In this case a full packet probably wouldn't hurt, but from what I understand yeast reproduction and the associated lag time help produce desirable esters in the finished product.

Since knowing exact cell counts is impossible, it seems that the problem would not be pitching more than needed, but, in technical speak, pitching WAY more than needed.

Well, this one is already going strong. I'm still waiting to see activity from the main batch that had 2 packs of Wyeast 1272 (no starter). I'm sure it'll be bubbling over soon enough.