One of the most common causes is a stuck or faulty air intake or gulp valve near the exhaust manifold. Backfiring can also occur with a sudden drop in fuel pressure. This may be due to a faulty fuel pump or a plugged fuel filter. Correcting problems in the fuel system usually resolves these issues.

“In general, backfiring on deceleration (as opposed to acceleration) is generally caused by a lean condition in the pilot circuit. Then when the engine does fire, these un-burnt gasses are ignited in the exhaust pipe, causing the backfire. Decel popping is caused by the detonation of unburned fuel in the exhaust pipe.

The most common causes for backfiring during acceleration include an incorrect fuel-to-air ratio, a faulty ignition and bad wiring. Backfiring during acceleration can also be caused by internal carburetor problems, low compression, leaks in the fuel tank, lean engine conditions, and weak or broken valve springs.

Backfires and afterfires are worth paying attention to since they can cause engine damage, power loss, and decreased fuel efficiency. There’s a variety of factors that can cause your car to backfire, but the most common ones are having a poor air to fuel ratio, a misfiring spark plug, or good old-fashioned bad timing.

A straight pipe exhaust will reduce the amount of pressure that is put on an engine by exhaust gases, which will let an engine function better overall. You’ll see an increase in both horsepower and torque when you put a straight pipe exhaust into place.

No it won’t. That’s a myth. Changes in the a/f and loss of exhaust velocity will affect torque.

It is true… you’ll Def lose low end torque but what you lose on one end, you gain on the other, i.e. horsepower. You lose that back pressure that the mufflers give you, but with the free flowing air from not having mufflers, the quicker the air exits the more hp you gain.

So, at low RPMs, backpressure actually increases torque, because the least amount of compression is lost through the exhaust valve ( due to back pressure ) during the intake stroke, and the ratio of intake to exhaust gases is high.

Even GM, probably the most outspoken carmaker regarding backpressure testing, suggests different readings throughout its carline. For most of its engines, GM recommends no more than 8.62 kPa (1.25 psi) at idle, and no more than 20.68 kPa (3 psi) at 2,000 rpm.

Conventional wisdom says exhaust backpressure is bad. If you want to maximize horsepower, the thinking goes, you have to minimize backpressure. Consider the ultimate low-restriction exhaust system: A Top Fuel dragster like the one you see above. As it turns out, backpressure is simply bad for power output.