If you still have the stock guts in the engine, you are limited to the amount of boost you will get out of it. If you intend to seriously go racing with the car, what are your plans and goals?
In general terms, centrifugal superchargers are similar to turbochargers - as you size them up to get more power, the amount of time (lag) needed to spool them up to their full power potential increases. They WILL produce extremely high power spikes, all things done correctly, higher than the output from a good twin screw positive displacement blower.
Overcoming any racing disadvantage from lag in either case requires planning, driving skill, and strategy. Lag is less of an issue on launch, where the rpms can be allowed to climb to the desired point, but CAN be a problem when gear change time arrives. Automatic trannies are the prefered method for winning in this case, with shift points and torque converter ratings designed to keep the engine in the fat part of the power curve, though really adept drivers can make a 5 or 6 speed sing through the power shifts.
The new twin screws overcome much (but not all) of the top end advantage of the centrifugal blowers, and some of the peak of the turbos, but they really shine in the area of torque production down low. They have virtually no lag, and the engines behave very much like a much larger displacement engine, hence their "positive displacement" tag. For street use they are hard to beat, with their instant response and fat power curve.
Frankly, if I were building a dedicated, cost no object, all-out race car based upon a 4.6, I would be looking at a big turbo rig.
For a daily driver 4.6, cost no object, I would go with a fully built bottom with a big twin screw sitting on top.
For a street/strip car, I might choose a strong ProCharger blower. I like their internal lubrication system.