Ford F-150: Exhaust Modifications

This article explores three of the most popular exhaust modifications for the Ford F-150 that combine engine performance with great sound quality.

By James Karuga - September 16, 2014

This article applies to the Ford F-150 (2004-2014).

The Ford F-150's exhaust system can be modified in one of three different ways: the single in/single out (SISO), single in/dual out (SIDO), and true duals. Each of the three modifications have unique performance and sound characteristics, and it’s up to the owner to determine which best suits his or her truck. Aftermarket cat-back systems on the whole will generally cost between $500 and $1,000. If you don't want to spend that much, you can ask an exhaust shop to build the piping for you. The result will be custom but less expensive than a prefabricated kit. Designing your own exhaust could be a fun and rewarding experience, especially if it sounds good in the end.

Exhaust Modifications

Single In Single Out (SISO)

F-150 Corsa Sport Exhuast - SISO
Figure 1. Corsa's exhaust for the F-150.

Price - $200-$1,100
Sound - Depends on muffler; Less aggressive than True Duals.
Performance - Better than stock.

SISO exhaust modification is the most basic for the Ford F-150 truck. It is Y-shaped and exits to a single intermediate pipe entering into a muffler with a single inlet and leaving the exhaust system by a single tailpipe. The Outboard Exhaust Manifold exhaust system, which can cost from $15 to over $800, is one variant of the SISO modification.

SISO modifications are also cheap, offer great towing performance, and look like the factory exhaust. However, they are deficient in aggressiveness, tone, and volume, and they perform poorly in higher revolutions per minute (RPM) range. In SISO modifications, the pipe's exhaust diameter in F-150 dating from 1997 to 2008 goes from 2.5 inches to 2.5 intermediate pipe and exits to a 2.5 inches tailpipe. This restricts the truck’s performance. However, a custom optimal 3 inch SISO from the Y pipe to the back without the tip gives the best sound quality and towing performance.

Single In Dual Out (SIDO)

Figure 2. MBRP's Cat-back exhaust system.

Price - $200-$500
Sound - Depends on muffler. Less aggressive than True Duals.
Performance - Better than stock; Slightly better than SISO at higher RPMS.

SIDO exhaust dual tip modifications are aftermarket's most popular setups for the Ford F-150. They only differ from SISO by the fact that gases exit the muffler via dual outlets and exit the system through dual tailpipes. This simplicity makes SIDO modifications popular with vehicle owners. They look like true duals, are inexpensive, and give good sound quality. But like the SISO exhaust modifications at higher RPM, they are deficient in tone, aggressiveness, and volume. SIDO optimal pipe sizes are like SISO, except for the muffler outlets and tailpipes, which auto experts advise should be 2.5 inches. This helps maintain good low end torque for towing and cruising. Costs for SIDO exhausts run between $100 and $500.

True Duals

Figure 3. The exhaust pipes leading into the muffler are attached to either cylinder bank. Exhaust gasses are separate until they hit the muffler and are split again.

Price - $200-$1,100
Sound - More aggressive, louder tone than stock.
Performance - Improved top-end performance.

True Duals exhaust modifications suit Ford F-150 owners who like performance and sound quality together. True Dual systems are named as such because each cylinder bank has its own exhaust pipe. The tradeoff is that one pipe is longer than the other since more bends are needed to run alongside the other pipe. The fuel tank on the driver’s side prevents the left pipe from being routed straight through. Consequently, both pipes go through the passenger side and split off past the axle depending on the exits.

True Duals have superior tone and volume and are aggressive. They also have good performance down low and up top. However, they are pricey and complex in assembly. Pipe sizes are different on True Duals with 2.25 inches for low end torque and 2.5 for top end power. Sound quality also changes with the two sizes to bigger and deeper. They cost between $200 and $1,100 depending on the truck and the brand of exhaust.

Pro Tips

  • If an exhaust pipe size is too small, the engine can choke and hinder performance. Auto experts advise internal diameter of the pipe to be between 2.25 to 2.5 inches at least.
  • An exhaust performance is defined by how quickly and efficiently the system allows exhaust gases to escape. This allows the engine to “breathe” better so that spent fuel and air exits the combustion chamber faster. When an exhaust operates at optimum, it means more fuel and air is burned, thereby creating more engine power. Larger exhuasts (3"+) are beneficial for high performance engines.

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