I'm running my steam through an Iron tank, and pumping steam from 4 (DenofLions) valve pipes to the Steam Turbine. Neither of my Boilers is able to keep up with the steam loss while the turbine is running.

Turbine fed by 4x Gold pipes, each fed from (DenofLions) valve pipe.
Aux Boiler, 2x2x2 HP Boiler (8 HP blocks) produces about 10% of the steam the turbine is drawing.
Main Boiler 3x3x4 LP Boiler (36 LP blocks) produces about 90-95% of the steam required.
Nuke Reactor (in a seperate, creative mode) should be producing 110 EU, but doing steam instead just barely outruns the turbine, producing about 110% of steam required.

Mods loaded:
Buildcraft A 3.2.2
Buildcraft Z Valvepipe MC1.4.5 mod 1.3.2
Forestry A 1.6.2.8
Industrialcraft 2 1.110
Railcraft 1.4.5b-6.10.0.0
Forge 1.4.5-6.4.1.410

Can I ask why you're using Valve Pipes for starters?
You don't pump out the Steam, a boiler is pressurized, It'll find it's way in to the gold pipe by itself.

Is this the correct version? Railcraft 1.4.5b-6.10.0.0?

6.11 doubles Turbine input.

Also try connecting the Turbine directly to the Boiler.

I'm piping the steam from the boilers to iron tanks, but then need the valve pipes to get the steam out of the tank to the turbine. (added benifit, allows a redstone switching mechanism to cut off steam to the turbine)

working perfect now, turns out my problem was in how I (personally) was using pipes. I didn't realize that adjoining pipes become much less efficient as they apparently swap fluid between themselves; thus my feeds from the boiler were far below the rated value of the boilers.

Oops.