In order to check out the results from the engine simulator (see simulation), we have done a limited amount of dyno testing.  In these tests, we have tested a car on a chassis dynamometer before and after swapping cams.  The tests performed are as follows:

These tests are not ideal scientific experiments.  Differences of less than one half horsepower are probably not significant.  More precise results could be obtained using an engine dynamometer, but unfortunately we do not have access to one.