hitting boost ceiling w/ WI?

[GTTechnics]

I currently own a centrifugally supercharged VR6 (VW) running 9psi of boost and 10:1 compression. I am preparing to change the pulley size to the smallest available (15psi). Due to space constrictions, a water/air intercooler is somewhat impractical, so WI seems like a good option. The company supplying the pulley offers fueling and compression kits (lowering to 9:1, 8.5:1, or 8:1). They claim that the 15psi pulley is safe to use with their fueling and the 8:5 to 1 spacer. On a side note I live in the desert (Arizona).

Assuming that the kit is safe, I have no control over ignition (other than what the CPU gives), I can't further increase the boost, and I can only tweak air/fuel ratios (straying from the above fueling kit) with an adj. FPR....how effective will water injection be for me? As far as I understand I will probably regain timing (and therefore low end torque),and be able to lean out my air/fuel to a more reasonable ratio (as well as provide more consistent performance on hot days and give a margin of safety).
Am I correct? Is there anything I have missed?