Cobb Tuning 3" 07-08 MazdaSpeed3 Street Downpipe Review » Introduction Continued

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2 - Introduction Continued

Introduction Continued:

The Cobb downpipe is probably one of their most engineered pieces to date. The bellmouth flange is a CAD designed investment-cast turbine outlet, made of 304 stainless steel for enduring corrosion resistance and reduced heat transfer to the engine bay. The shape of the outlet flange makes optimal use of the tight confines of the MS3's engine bay, smoothly blending turbine outlet and wastegate gases. The outlet flange is configured with two O2 sensor bungs; one to accommodate the stock O2 sensor and another with a pre-installed plug that can be removed to allow an aftermarket wideband O2 sensor or datalogging device with easy engine bay access.

One of the most interesting aspects of this downpipe is the custom spun metal substrate high flow catalytic converter. This one piece 400 grade stainless steel cat has a much higher flow rate and longer lifespan compared to ceramic or “brick” style cats. It also reaches operating temperature faster than other style cats for cleaner cold-start emissions. A third O2 sensor bung is located immediately after the cat to be used by the second OEM O2 sensor. We tried getting a good shot of this converter but its nearly impossible without a bore scope or a converter all by itself. Its definitely a beautifully constructed piece and is quite small in size.

The stainless steel flex section used in the COBB 3“ Downpipe is internally lined (unlike most flex sections) and provides smoother exhaust flow and much longer lifespan for the steel braiding. The placement of this flex section in the factory location (before the first exhaust hangers) is critical in absorbing engine movement and eliminating damaging stresses that would otherwise be applied to the flange, cat, exhaust hangers and chassis. This increases the longevity of the downpipe as well as downstream exhaust components. This piece is what ultimately increased the end price of the downpipe when it went to market.

All tubing used in the fabrication of this downpipe is polished 304 stainless steel for increased corrosion resistance and a mirror-like finish. The 304 stainless steel hangers are cross-welded and well braced to eliminate a point of fatigue that is evident in other aftermarket downpipe designs.

The end flange uses the stock donut gasket and factory spring bolts to aid in flex, longevity and proper fitment. This provides an improved seal compared to other methods, as well as reduced noise. An additional benefit is that it makes the COBB 3” Downpipe compatible with any cat-back exhaust that mates to the factory cat section. Although you see the end portion of the downpipe neck down to 2.5" near the flange, it doesn't seem to affect the flow of the exhaust whatsoever from driving around with the pipe on for 400 miles.

Another thing i noticed while looking at other downpipes out there is, the Cobb has the least amount of bends in its design. This is one of those downpipes that looks good on a wall, rather then in the car, since much of it is hidden.

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