I think theres more to it than just the cams... I was looking at this the other day. theres Compression, the cams and the computer.

 

You'd need the higher compression to properly burn the hgih octane gas. The extra 30hp would be nice but filling up my V6 on regular takes some getting used to. The Spec V Sentra got 26mpg with me driving it and only held 12.9 gallons. I got between 280-300 miles per tank. Now I get 320miles a tank but the tank is twice as big!! Ain't no way in hell I'm filling it with 93 octane.

 

My last car got ~330 miles a tank with a 13 gallon tank (might have been slightly smaller but right around there) on 93 octane. Anything below 93 it didn't appreciate much.