have 875 holeys on motors now 500hps making about 575hp also have a buddys 875 bg demonds only 2 years old what is the better carb and what can expect to gain 1 over the other.

Neither will make much more power than the other. The demon is harder to adjust out and harder to find parts for at every day auto parts stores if you need them.

I always go with the Holley for consitency and ease of maintenance.