Headers are one of the most common, affordable methods to increase horsepower and torque right behind getting an aftermarket intake. Headers are also one of the easiest bolt on modifications and are designed to increase the efficiency in which exhaust gases are expelled out of the cylinder heads. Headers are an added benefit to allow exhaust gases to be scavenged out of the cylinders more efficiently so there is not so much work for the engine when the piston is moving back up on it’s exhaust stroke. Just imagine how you are modifying your car to introduce air for a nice combustion to force the piston down, which turns the crank to make power. But in another cylinder if enough back pressure from insufficient exhaust flow is present it works against that power stroke defeating your efforts!
On California spec models of cars, with the increased use of catalytic converters creates a situation where manufacturers are forced to use exhaust manifolds. This is done to accommodate for space restraints when introducing pre-cats into the mix. Other cars with emissions not so stringent such as Federal Emissions specification vehicles, manufacturers design cars with exhaust manifolds which resemble headers with longer runners.
These exhaust manifolds create a situation where exhaust gases collect right outside the head and merge right into one chamber with 2-3 other cylinders ready to push exhaust gas in within a few seconds of each other. This creates an inefficiency like cramming too many people into a subway car, thereby the engine has to work harder to cram more people into that subway car.
In order to reduce or potentially eliminate this problem is through the use of headers. Each cylinder gets it’s own exhaust pipe and allows for the exhaust gasses to travel a further distance to cool down before it collects with the other exhaust gases to eventually flow out of the back of the car. With the RPW headers, all of the header lengths are equal so all the exhaust gases reach the collectors evenly spaced out enough to reduce the amount of back pressure as much as possible. This makes your engine happy! This means that there will be less resistance on the exhaust stroke which means a more hearty power stroke, and that equals more power.
Short Tube vs. Long Tube
The difference between short tube headers and long tube headers is where the power is shifted in the power band. In terms of short tube headers you will see more peak horsepower, this is better for 5 speed vehicles that have low end traction issues such as wheel spin and wheel hop. The long tube headers make more overall torque but tend to shift the power gains down towards the bottom of the power band. The long tubes are more optimal for automatic cars since they tend to lag down low in the power while the torque converter is engaging.