Here’s some more information that adds two more sets of headers to the list of those that have already been tested. These were also tested on the same engine combination as all the other exhaust systems which keeps comparisons equal. Whereas only the best scores for each exhaust system were previously posted regardless of the number of configurations tested, here are the scores for each tested configuration for these two sets of headers. The scores are still based on the overall performance in the 2300-5500 rpm range.

As in the previous tests, the mufflers continue to be appropriately sized based on the size of pipe that’s used in each test. In the FPA header test chart below, there were three different pairs of mufflers being used. The Ford Powertrain Applications (FPA) headers were unique in that the best numbers achieved were without any exhaust extensions being used and part of this could be attributed to the merge collector design being used at the ball shaped muffler connection at the end of the headers. Many of the headers being tested did like some form of exhaust extension in which to improve their overall performance.

Crossover pipes were also tested and you can make your own assumptions based on the numbers. Sometime in the near future, I’ll post the lower rpm band information which is where the crossover pipes appears to make the most difference when comparing the graphs.