Quote: ..i agree, 2 1/4 is plenty. ..i'm not convinced mandrel bends are an improvement. ..i ve read tests that show only 12 or 15 hp increase with open headers on a 300 hp build.
300 Hp is relatively mild and 2 1/4 is probably adequate (I think that is stock size for a 383). I think you should continue your research on the value of mandrel bending as well as the combination of horsepower and torque with different exhausts. Also 15 hp is 5% of 300hp.
