waynesworld>
The .63 will give you better top end and the .48 will give you better low-mid range. I would expect the .48 to get you near 300 ft/lb torque at 3200 rpm and the .63 to be in the 4800 rpm range. Driving the .48 is more impressive because it comes in at a lower rpm and will have a stronger pull (Stop light to stop light acceleration will be Excellent). The .63 will not feel as punchy to drive (smoother) but the dyno results will be very impressive.

Additional injectors are the best way to start. I prefer the HKS AIC (First Generation) controller. Keep the box near you so you can tune it easier. With this controller I can tune the flat spots out faster than trying to play with a laptop. You can also play around with the Control Pressure Regulator. I have been trying to figure out a way to send varied resistance to the CPR at different Boost levels. I made a relay control box before but had trouble trying to get it just right. It ran either too rich or too lean.

On another turbo project I used 2 injectors with 2 pressure switches set at different boost levels to switch on each injector.
One at 5 psi and the other at 10 psi.
Cost was less than $100 and it worked great. Simple but effective.

Using Additional Injectors also has a plus it cools the air charge about 10-20 degrees.