A well thought out tunnel ram intake and corresponding two four barrel carbs will out perform a single four barrel system hands down. The trick on the street is to keep runner size long and narrow, to help with low speed operation. Tuning for driveability is the issue and requires some work. However, you cannot beat a tunnel ram for high speed operation.
I will say this, however. I do, however feel it's a waste of time to use one for performance if you don't intend to twist it over 6500 RPM. If your intended RPM range is under this, I would probably stick with a single four barrel.
On drag engines that I have dyno'd, I have seen as much as 75 or more horsepower increases with a tunnel ram vs. a single four barrel system. They just work that much better over 7000 RPM, and even though they seem "old school" they are still the ultimate carburetion system. I firmly believe that the atomization capability produced by the large plenum of a tunnel ram offers better top end horsepower over injection.