Headers vs. Exhaust Manifolds ~ 'Let The Debate Begin'

wait up guys, lets look at some math: exhaust pulse travels 350 ft/sec or 4200 in/sec. A log is about 18 inch long at its longest point (#1) so at 2500 RPM which is a average cruising rpm, the exhaust pulses are hitting 40 times a second to each bank of manifolds. That gives each pulse 105 inches of "space" so the notion of an exhaust log feeding a 2" head pipe getting "backed up" with other pulses is nonsense. even considering reflections, you cant believe you are introducing a bottleneck. The header design is to enable an exhaust pulse to pull the next one out with it, enhancing cylinder evacuation and filling due to the small overlap portion that pulls more A/F in. Running a set of headers on an stock untuned (for headers) motor (carb untouched) will not show much gain but tuning for headers will show an improvement in HP and even more in torque which is what you can feel. Manifolds are not that bad considering their design restraints. Look at some old graphs of manifolds vs headers on a stock motor running designed RPM's and the results will suprise you. They are hardly worth the effort on a stocker, but even simple tuning will really wake up their potential. Whats 10% of a 318's 140 hp? 14 hp. Yeah! But on a mild build 300 HP 340, thats 30.