One of the biggest power restrictions on the Mazda 6s is the factory exhaust system. The entire factory exhaust system is a huge source of backpressure. Both front and rear exhaust manifolds are very restrictive due to their hydro-formed construction, shape and size. In addition, both manifolds contain a pre-cat, which is a catalytic converter before the main catalytic converter. Traveling back from the front pre-cat to the front-secondary cat, there is a very sharp 90-degree crimped, bent and welded "pipe" that creates even more restrictions before dumping into the secondary converter! As for the rear manifold, after its pre-cat, the stock routing makes a power robbing 180-degree turn, and then snakes its way through many sharp bends to its final converter. The stock y-pipe also changes diameter a few times, causing pressure variations that rob the engine of even more horsepower.

Knowing this, Custom Performance Engineering™, Inc., (CPE™) designed a free-flowing system. First, they determined that the stock routing was the primary cause of the restriction, then CPE chose the best possible path and designed a header system to fix the problem. CPE decided to build an equal-length, 304 stainless steel header with a 304 stainless steel Y-pipe. Long tube, equal length headers increase mid and top end horsepower.

In addition to the primary length, close attention also must be paid to the collector. Through extensive testing, CPE determined that a 2.25" collector was the ideal size. The collector also was designed to be as long as possible to provide a smooth transition from the primary tubes.

The Y-pipe features two stainless steel catalytic converters. OEM Y-pipes are made with ceramic converters and are known to fall apart. Stainless steel converters will last far longer than the OEM ceramic ones and put up with years of abuse.

Below, you will find a picture of the OEM Mazda 6s Exhaust system. Note the many sharp bends, U-turns, and the 4 catalytic converters that your poor engine has to pump against! Note the extremely short 90-degree turns the front exhaust ports must face, only to dump immediately in to the power robbing front converter.

The horsepower and torque dyno charts are available below. Peak gains were 20.34 horsepower and 18.39 ft-lbs of torque.

The CPE headers are also pictured below. The CPE headers also include an alternator relocation bracket. Due to the many requests, CPE recognized that many of the savvy Mazda enthusiasts will want to create their own header-back "true dual" exhaust systems, therefore, to keep costs down the additional items needed for a complete kit may be added below. Customers desiring a complete, all-inclusive kit will need to add: a longer accessory belt, CPE Y-pipe of their choice, (with cats, or off-road), and oxygen sensor wiring harness extensions, all of which may be purchased in the menus below.