5.0 Mustang & Super FordsHow To Engine
2011 Ford Mustang GT BBK Headers Install - Nature Hunt
BBK Seeks All-Natural Coyote Power With Its Tune-Free Bolt-Ons
With that said, bolting on the BBK short-tubes showed they gave a substantial gain in torque below the torque peak, but at the midrange they lay down flat, before picking up 2 hp again around the horsepower peak. The dip is likely the engine management curtailing torque, but the short-tubes did worse than the long-tubes in the midrange, so there is something in the tube length as well.
A bigger, more established change came by adding BBK's X-shape crossover pipe to the end of the short-tube headers. This gave a gentle but definite lift up across the tach, but especially north of 3,500 rpm. The power peak reached 368 hp and 351 lb-ft of torque and in general the combination of short tubes, X-pipe seem to be worth 5 hp and 3 lb-ft over just the short-tubes in our test.
The final test in conjunction with the short-tube headers was BBK's prototype cold-air intake. This was definitely a happy rpm addition, building power starting at 3,500 rpm, but with authority from 5,000 rpm to the power peak, where it added a solid 7 hp to the party. And, as you'd expect, it gave a big throaty roar in the process.
All told, the combination of short-tube headers, catalytic X-shape crossover, and cold-air inlet was worth just shy of 12 hp and about 8 lb-ft of torque at the peak compared to the stock baseline. Remember, too, that this is measured with the transmission in Fourth gear; the same tests in Fifth gear would add a horsepower or two, and an easy 10 lb-ft of torque.
* These are dyno results from tests conducted on BBK's in-house Dynojet chassis dyno. All tests with short-tube headers were run in Fourth gear; those with long-tube headers were run in Fifth gear. Therefore, figures from the two test series should not be directly compared.