Cobb Tuning 3" 07-08 MazdaSpeed3 Street Downpipe Review
 

Introduction:

Just a few weeks ago, Cobb Tuning sent us their Catback Exhaust system to review. We had a very good experience with the quality, fit, finish and tone of the system. The only thing missing, was the downpipe, to make this a full turbo back system. Cobb Tuning came through and sent us their 3" Mazdaspeed 3 Downpipe with High Flow Converter well over a week ago. Unfortunately we had a few issues when we attempted to install it last week. These problems suffered were not Cobb's fault... they were of course, Mazda's...

For some, you probably haven't heard of the headaches Mazda brought upon our niche platform. For starters, their Oxygen Sensors ( Wideband up top side, Narrow Band Post Cat ) have a fine thread pitch. Unlike most vehicles out there that use a NPT type thread on the O2 sensors, Mazda had to be a bit different... But, it doesn't stop there. The material that Mazda chose to use for the threads is the weakest metal I've ever seen on an exhaust system. What do i mean by weak? I'm talking about the metal being extremely soft. Whichever method Mazda has chosen to install these sensors, surely can wreck havoc on your beloved install. Mazda either used extremely high torque to install these pieces in the exhaust system or they designed the threads to self destruct upon removing these pieces.

For awhile now, our community has been trying to caution the end user when removing their O2 sensors. We have gone to great lengths by telling people to use a can of PB Blaster to soak the threads and use extreme caution by going 1/4 turn in and out to work the sensor out. However, you have a 50/50 chance of the threads becoming destroyed while you remove them, despite, how careful you are. This is what happened to us, but... We are lucky. Our Wideband sensor, which by the way is the most expensive, came out effortlessly. The Narrow band which is post converter, was our problem child. i devoted over 60 mins to working this monster out of the pipe, only to be greeted with complete & epic failure. Since i wanted to get this install finished and the Narrow band was destroyed, i gave a call to 5 local Mazda dealerships in my area. The most amazing thing happened, each quoted me a price of $198 and guess what? NOT IN STOCK. Amazing, each and every time I've needed a gasket or something along those lines, everything seems to be special order. I'm guessing Mazda only stocks air, cabin and oil filters for our cars, nothing else.

At any rate, i stuck a plug in the O2 bung and called it a day. Thank god this car can drive trouble free on that sensor since its a non heated sensor. In the meantime, Robert over at EDO Performance saved our butt by locating a Bosch replacement sensor for only $60. Funny thing is, it arrived quicker than Mazda could get one to me and the threads aren't like the OEM junk one's Mazda is pawning off on us for double the price.:hitwithrock:

All of this occurred on the day before Thanksgiving. 3 days before that, the first attempt to install this downpipe failed. Yes, failed... You see, mileage doesn't seem to matter on these cars. It all boil's down to who assembled the car on what day. When I attempted to break the flange bolts loose on the stock downpipe, i broke a stud in the manifold. It was the lower right stud which wasn't all that difficult to remove. At the time, i thought i was the only who broke one of these suckers. However, I'm hearing from our community, that some other owners had some issues with theirs as well. It seems, some days Mazda put something on the threads during assembly, other days, nothing... as if they ran out of the gogo juice or something. I guess our car was a non gogo juice day because something this simple, ended up being, the most difficult thing i have faced on this car. Out of 5 flange bolts, 4 studs came out with the bolt still attached. With the help of Logan at EDO, we made an attempt to remove the bolt using a vise to lock the stud in. We just wanted 2 studs to hold our gasket in place while we got the bellmouth attached to the manifold. 4 turns into removing the bolt from the stud, it wasn't coming out & it stopped backing off the thread. Again, Mazda used some kind of anti enthusiast glue on their studs/bolts. So, we said screw it and used it as is.

I don't want to try to scare anyone who is going to install their own downpipe on these cars. I'm all about shade tree installing performance parts and persons new to this whole thing really should dive in and lose your newb status... but these are things you must know in case you have a similar problem like we did. All i can recommend to you is a lot of patience and time on the table to do this. Some members have done a DP in two hours, others 6 - 8 hours. Total hours for our install spread over two separate days was 15 hours.


[multipage=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.

[multipage=Tools Required & Some Advice:]
Tools Required:

• 3/8 Ratchet
• 10MM Socket Deep & Medium
• 12MM Socket Deep & Medium
• 14MM Socket Deep & Medium
• 7/8" O2 Socket
• 10MM Open/Box End Wrench
• 12MM Open/Box End Wrench
• 14MM Open/Box End Wrench
• Needle Nose Pliers

Recommend Advanced Tool List:

• 1 Can of PB Blaster
• Downpipe to Manifold Flange Gasket
• Mazda OEM Donut Exhaust Gasket
• Anti Seize
• Wobble Joint
• Universal Joints
• Multiple Extensions ( Long & Short)

Recommend Prosumer Tool List:

• 14mm Ratcheting Wrench
• 12mm Racheting Wrench
• Stubby 3/8's Ratchet
• 3/8 Impact Gun

Yes, that does say impact gun. Had we not had that available to us, this downpipe would still be sitting in the garage. Some so called experts claim that you will snap your studs using a gun. You couldn't be so wrong. I snapped the stud using a ratchet with a pipe as an extension. The Impact is what broke the studs loose for us without destroying them. We would back the stud out 1/4", then thread it back in. By the third time, the stud came out like butter. I'm hoping this is just a small, isolated incident among cars. Our MS3 has 27K on the odometer and i didn't expect seized studs and bolts. But, we are over the hump now and it's on the car. I do recommend having a buddy around to help you out on the install. Anyhow, enough with my rant as we have successfully got the downpipe installed. Follow through my pain and enjoy the review i have created for you. There is some good referencing during this install you are welcomed to. BTW, Since our car has a COBB Front Mount Intercooler installed, we skipped a few steps requiring you to remove the Factory or ETS Top Mount Intercooler.

For those who are wondering, the part number for the Bosch replacement sensor:
F00E262571 - BOSCH

[multipage=Cobb Downpipe Installation]

We started our install a bit differently then how the Cobb instructions are laid out. Since we had the car on a lift, we chose to attack the bottom portion first. First step, is unbolting the race pipe or stock mid pipe section, from both the catback section and stock downpipe locations. You will also want to remove the large metal skid plate and the horizontal cross member in order to make access to these areas easier. See below:

[multipage=Installation Continued]

[multipage=Putting It Back Together]



[multipage=Back Together Contiued]

[multipage=Finally Done]


[multipage=Conclusion]

Conclusion:

Wow, what really is there left to say? For some reason, this was the hardest thing i've had to install on a MS3. The pipe itself is easy to install... Between the flange bolts that wouldn't break loose & the O2 sensor that munched itself, it makes a person frustrated. I hope you take something good from our review because i think i could have been better prepared had i had some kind of guideline to go by. Im kicking myself for not getting a new gasket for the bellmouth flange area. Since Mazda doesn't stock anything for this car in Socal, we had to reuse the stocker piece. Perhaps, we will be lucky and not have to deal with replacing it.

Now, with the downpipe installed, the car really comes alive. The EGT's dropped 168 degrees from my current tune. The car pulls really good up top as well. I have really strong midrange power now. The most impressive thing is how very little noise this system makes with the addition of the Cobb Catback on there. Wide open throttle runs on this car have a very Subaru type of sound to it. i find myself going WOT as much as possible now just to hear the new exhaust note this combination has created. Im very happy with the car but im also happy to see Cobb kicking out more parts for these cars.

We will get some sound clips up later, so look for an update.

Cobb will be releasing their BPV and Turbo inlet pretty soon. They are also working on the Mazda software for end user tuning on the Access Port. In 2009, Cobb is set to release more advanced suspension for our car using true 1 and 2 way coilover setups.

Again, i would like to thank everyone at Cobb for sending us their Downpipe for review. There is nothing i can recommend on their end that they fix or address on this downpipe. Fitament and quality is perfect on this Downpipe.

I would also like to thank Robert, Edwin & Logan over at EDO Performance for giving us the grips on the shop location, being hospitable and putting up with us! Robert came through on a new sensor for us right after the holidays. This a nice shop for those who are big into Subbies and EVO's. They are now doing Mazda stuff. They are also an authorized Cobb distributor and tuner.

If you have any questions or comments about this review/install, please visit this thread.

Sources:

Cobb Tuning
Salt Lake City, Utah
CobbTuning.com - Home Page


EDO Performance
Huntington Beach, CA
EDO Performance.com - Performance Parts for Subaru, Honda, Toyota, Nissan, from Zero Sports, HKS, GReddy, Defi, Tomei, Jun Auto and More