Originally Posted by 70GS455
Going from 56 psi (stock) to 76 psi (assuming 20 psi boost) of fuel pressure with a regulator which tracks with boost should net you a 16.5% increase in fuel delivered - as long as the pump can keep up. Based on the flow chart I posted, with the stock pump I feel that this may become an issue. It appears that the stock pump might not have sufficient capacity, especially if the injectors are running near 100% duty cycle (static).
It's not the difference in pressure, it is going from 55-60g/h (stock) to the 95g/h that the SL55 pump gives you. Up top you are loosing pressure in the rail due to lowered volume. The SL55 pump adds 35-40 more gallons per hour.