Stock Exhaust Manifolds vs. Hooker Super Comp Headers
We actually ran this test in reverse, as we had previously installed the Hooker headers on the 4.6 GT motor. Once we were finished testing the cams and Accufab throttle-body, we decided it was a good idea to see how much power the Hooker headers offered over the stock manifolds. The headers were run with 3-inch collector extensions. This open-exhaust system allowed the motor to produce 307 hp and 345 lb-ft of torque. Installation of the stock exhaust manifolds and 2.5-inch manifold (collector) extensions resulted in a dramatic drop in power. The stock manifolds dropped the peak power to just 268 hp. The peak torque was down as well, from 345 to just 318 lb-ft. The restrictive stock manifolds dropped the peak torque production by 500 rpm (from 4,100 to 3,600 rpm), a clear sign of a restriction. View Related Article
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