Please DO NOT use a aftermarket pulley for your S/C. It really is close to max rpms (s/c impellers)right now, and the extra boost is negated by the increased intake air temps (quite high w/9lbs of boost) you WILL detonate (causing the timing to retard)and possibly melt a piston, or crack the bridge between the valves, if you detonate or go lean for long periods. The fuel system is lacking. If you put a proper sized fuel pump on there you will see that the injectors are running over 80% duty cycle and will actually flow less gas.The URD kit will fix everything and more. Like dialing out your mid-range ping and controling your fuel, exaust gas temps and fuel trims. A obd2 scanner will help allot because you can check out the logged data and really dial in the proper tune. Every truck needs custom tuning (on dyno for the best results) and monitoring of the engine systems is critical. With all the right equipment you CAN use more boost but with our set-ups it's pushing the limits.
Just my $.02(b-4 taxes <img src="/forums/images/graemlins/lol.gif" alt="" />)

P.S. some are using the 9lb, 9.5lb and 11lb pulleys. Those guys have fuel mods and monitoring equipment.