[mynameisvlad]

Japan's shinkansen travels at 2-2.5x the speed of the Acela. At the maximum speed of current bullet train technology, Boston - NY could likely be done in about 1.5 hours, Boston to Washington in about 2-3, and even Boston to Cleveland in around 3-4. That basically covers the entirety of travel in the Northeast corridor.

This doesn't even cover the new maglev trains that are expected to go into service sometime in the late 2020s in Japan, which have a maximum speed of 550km/h, expanding the range of that 4 hour "maximum" significantly.

The major problem with the Acela is that it mainly runs on older infrastructure that wasn't designed with HS trains in mind. This severely limits its speed on most of its route. Most HS systems in other places around the world are on newly developed HS lines that were built up specifically to support the much faster speeds and requirements of these trains, and are completely separate from the regular rail lines (which might be running in parallel nearby).