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Cobb Catted Downpipe

6K views 4 replies 4 participants last post by  FrankRodrigue1 
#1 · (Edited)
2013 Subaru WRX Hatch, Satin Pearl White
Cobb Tuning SF Intake + SF Intake Box + PTP Turbo Blanket
Torqued Performance Stage 1 Rev9 E-Tune
Whitelines Anti-Sway Bars, Kart boys Endlinks, Back to black bushings.
Roof Rack,Bike Rack, Cobb Knob, Gorilla Mud Flaps, 40,000 Lumens of light bars
91 Octane Shell/Chevron fuel ( CA Blend )


Backstory:
So Ive had a pretty good few months at work and it has left me with some spending money. Im not ready to do a big brake kit yet and everything else is in good working order so I decided it was time to treat myself to some exhaust. In previous Threads I have expressed my belief in high flow cats so I am going catted and I voiced my concerns over loud exhaust as I often leave the house before the sun rises and I don't want to be excessively loud to the neighbors. I also like the idea of keeping things stock looking so that I don’t attract too much unwanted attention from the authorities. In order to keep everything quiet I am mating the new down pipe to the stock cat back system. In my reading the restriction from the stock cat back is negligible even at stage 2 power levels.

Why Cobb?
I decided to go with the Cobb Catted down pipe option for 3 reasons. 1. I liked that the catalytic converter is further downstream than all the other options. That means that at least in theory there will be less heat up in the engine bay and when the car is moving that the heat from the cat will be pulled away by ambient air. 2. I choose Cobb over nameless because I don’t want to wait 3-5 weeks for it to be custom welded. I may choose them for a 3 inch turbo-back race exhaust but I am currently spending most of my time sitting on the freeway rather than tracking the car where additional volume would be acceptable. 3. I choose Cobb over Invidia because I dont see the need to run a divorced waste gate in a belmoth housing. The extra 4 inches of reduced turbulence doesn't make sense in my head. For a similar price I could get the Nameless part but both Nameless and Invidia have their cats located up in the engine bay. Finally I choose cobb because they use the stock donut gasket. That means I don't need any adapters to mate the down pipe with my stock cat back.

Install:
The install process was pretty straight forward. Pull the stock down pipe and drop in the new one. Definitely a 2 person job though, keeping everything aligned during the install. Me and a friend installed it in less than 3 hours, a majority of that time was cooling the car down and removing all the factory heat shielding to get to the bottom turbo bolts. We spent a considerable amount of time trying to figure out what the PTP Lava blanket was snagged on and shimmy it out of the way. Removing the OE down pipe was easy enough following Cobbs written instructions but the instructions failed to mention a few of the heat shield parts that needed to be removed and were not part of the final reinstall. The only part I had a difficult time with was the hanger bolt towards the rear of the setup. The Cobb down pipe fit perfectly into the bracket that was mounted to the side of the transmission but the bolt hole did not align, rather than put additional pressure on the down pipe I used a 304 stainless cable tie ( think zip tie ) with a 200Lb break force to attach the down pipe to the face of the bracket. I will grab a photo for example next time the car is in the air. After installing the catted down pipe I turned my attention to the heat shield. I choose to run the matching Cobb heat shield just because it is nice a copacetic with my intake and intake box. It installed using 3 bolt locations and it is nice and snug over the top of my PTP Lava blanket.

Testing:
I got ahold of Eric from Torqued Performance and we worked out a tune for the Catted down pipe ahead of time so after the parts were installed and the car was back on the ground I remapped and started the car up. It sounded a bit deeper, maybe more rumbly, wetter than before I suppose. It smelled like a new exhaust pipe/heat shield for the first few minutes but the smell quickly dissipated. I let the car idle until it got up to temp and took it for a spin. The Stage 2 tune from Torqued Performance is fantastic. Its more torquey at the bottom end than their Stage 1 and the boost seems to jump right back after shifts. I was concerned that eh Cobb heat shield is a show piece rather than a real heat shield so I measured the temps with my V3 accessport. Measuring temperatures for intake on my post install drive I was hovering around 25 degrees over ambient. As far as I can tell the PTP blanket is still doing its job and I would assume that even without any heat shield I would be in a similar position. I took a few logs and other than a tiny bit of Fine Knock Learn in the logs everything is looking solid. Eric has already sent me a Rev 1 map to load up and I will continue with the tune/log/revise pattern until we are dialed in.

Final Thoughts:
I am very happy with my Cobb down pipe. The install went according to plan, the fit and finish are excellent and the sound is a bit deeper without being excessive. I am very pleased with the performance of my new down pipe and the car in general.

** Sorry for the edit I forgot to post pohotos **





 
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#2 ·
I love your detailed, helpful and informative posts, Jason.

Have you a picture of that "304 stainless cable tie ( think zip tie )" downpipe fastener? Seems strange that the COBB DP wasn't a direct bolt in item.
 
#3 ·
Yeah I ran out to the parking lot to grab you a photo here it is. I thought it was weird that the Cobb part wasn't a perfect drop in as well but as far as Im concerned it was perfect where it mattered, mating with the turbo and the mid-pipe. If you look close the bolt seems to be welded a bit high up on that carrier. Rather than put stress on the turbo I let the exhaust sit in the hanger and attached it with a nice sturdy steel cable tie.

 
#4 ·
That's a trouble spot not exclusive to Cobb. My Invidia V2 Downpipe in my 03 was stubborn there too. Nice install and a good write-up too. You really have your head in the right place. Well done!!
 
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