What can of h.p. increase can you expect for each pound of boost, 1 pound =ect. is there such a formula.

 

it's like 25 hp for 1 psi upped so if you add 2 more psi u gain 50 hp. give or take a little. at least that's what I have read and heard

 

I would think that all other things being equal, that for every 14.7PSI of boost you add what your Naturally Aspirated horsepower number was (prior to boost), so if you were at say 275RWHP before going boosted, every 1PSI would be 275/14.7=18.7HP/1PSI extrapolating that out for 6lbs would give around 378RWHP, for 12LBS would be 499RWHP, etc.
If you look at rated crank horsepower of 300 and 12PSI boost, you get 544HP, which is pretty darn close to what whipple says their HO kit is good for.

But that's just my gut feeling on how you would calculate it. Based on sea-level air pressure of 14.7PSI and the fact that you try to keep the air to fuel ratio the same.