DIY 987.2 High-flow CAT upgrade

Hello Planet-9 New member here with only a few posts, first time Porsche owner and first time big project for the Cayman ! (other than coilover install, woof!) While I was shopping for Caymans , what to do with the exhaust was always on my mind. I definitely wanted a car with the sport exhaust ( PSE ), not a deal breaker, but I lucked out and found one, I love they way they sound with headers or Carnewal HFC mod; I figured that for the ~$1500 price tag for Carnewal , and $2500+ for header options, I have the tools and skills to give the Carnewal mod a shot....so, here we go: Night #1 OEM headers out, you can see the density of the OEM cat Made a crude jig in case my cuts weren't great, but they were pretty decent Case split No more cats Aftermarket 200cell cat Much lower density Cut off the transitions (those will be going in the stainless bin! I shimmed them to be as close to centered as possible, tacked one end, then did 4x rosette/fillet welds to ensure they dont break free and rattle I marked the cases prior to cutting, then lined them back up, tacked them together and put it back in the car, it fit really well, so took it back out and burned it in.....all in all from putting the car up on the lift it was about a 2.5hr job, for the passengers side...

Night #2 Knocked out the drivers side, didn't get a chance to install them, but that was okay because I needed to run to the hardware store and get some new fasteners for the collectors. Hoping either tonight or tomorrow night I can get everything installed and get the X-pipe installed and see how it sounds....eagerly anticipating that first cold start https://********.com/forums/graemlins/rockon.gif It was pretty much rinse and repeat, drivers side also has a mount/support on it which certainly helped keep things in position. Drivers side complete Got a photo of the OEM cat when I split the cases, also for got to mention that the cat is also on both sides of the O2 sensor, so there will certainly be a huge increase in flow. OEM cat Aftermarket 200c cat

That is awesome. Thank you for taking the time to share this mod. Excited to hear your thoughts once you run them in the car. [emoji1319][emoji1319][emoji1319] Sent from my iPhone using Tapatalk

Thanks! Got everything finished up last night, just in time for rain today which means no test drive ...Soul PP X-pipe fit great and looks so much better IMO Untitled by fouckhest , on Flickr Untitled by fouckhest , on Flickr Untitled by fouckhest , on Flickr Untitled by fouckhest , on Flickr Cold start video, guess you have to click on the photo to make it play....not sure why it wont embed?? Untitled by fouckhest , on Flickr

Awesome! Have you considered doing this for others? (nudge nudge)

The thought had crossed my mind

Interested if you do... I was just talking with Carnewal about shipping my stock R manifolds over for this treatment. Shipping is expensive!

shoot me an email and we can discuss....my screen name at gmail

How did you like the sound? P.s, nicest garage I have ever seen!! Sent from my iPhone using Tapatalk

Nicely done. I believe the oem cats are 400 cell

I really haven't had much seat time, I did get out a little yesterday and it certainly seems to sound much better, especially when getting into it...I need to get someone to video a drive by. Thanks on the garage, been a fun project over the last couple years. Thanks....I would have thought 6-800, but thats just a "gut" from the look of them.

Nice mod! I didn't replaced my cats but did buy aftermarket 200 cel cats from a named brand. They sound absolutely awesome but the CEL light come on with the usual cat inefficiency code P420 after about 25 miles of highway driving. I had already replaced the injectors, coils and reman injectors since the car is over 100K so yeah, Im pretty sure the new cats are the culprit here. Otherwise the car runs great and passes the yearly emissions test but I wish there was a way to lower the threshold of the ECU . I will have to learn to live with the CEL. The issue with this is that you don't know if it is the cat code or something more serious.

I've got a few miles on my car since the mod, no CEL yet; about to head up to ToD for the weekend, so will certainly put some miles on it over the next couple days. I'll report back.

So the mini cats I purchased kept throwing a code, so I went back to my original CEL fix type mini cats. They have to be the 90 degree style bungs. This allows the second o2 sensor to function properly. Mini cat for O2 sensor bung, 90 degree Check out the deal on Mini cat for O2 sensor bung, 90 degree at Racing Dynamics www.racdyn-usa.com

Awesome!! I did something similar - I got my hands on a set of 987.2 Fabspeed headers that had the cats blown out, so I made some jigs, cut out the blown HJC cats, got some 200 cell aftermarket cats and had an exhaust shop tig weld them in for me. Even with O2 spacers I couldn’t clear the CEL, so FVD tune was next . Best sounding car ever now with PSE valves open also.

Very Interesting, I dont have many miles on my car since doing this (maybe 1k), but "knocks on wood" still have not seen any codes for anything o2 sensor related. Definitely enjoy the sound with the PSE opened up.....although, I really need to get some one to drive it so I can hear it from outside the car

After installing these, you don't have check engine light anymore?

I've been running this set up for years now without issues.

So, if you live in a state that checks your exhaust to pass the test for a license you do need to use the cats. If your state does not test the exhaust , then all that is required is a long tube from the headers to the muffler. You also will need a ECU flash to turn off the O2 sensor . I use Softronics Flash. Scott will help you out. His flash will give your ECU maps that are about 10 times the data points , which means a much smoother delivery of fuel maps, ignition advance and related air flow in the intake manifold. This is an excellent time to add those long tube catless headers from Soul . I did and do not regret this decision. Their catless headers provide about 15 real HP increase. Also, if you think about the upper manifold upgrade to a 82 mm throttle body, now would be the time before any ECU flash. I used the Softronic Race Kit which uses the GT3 78 mm throttle body. This system is really great for those who are looking for mid range torque improvement some HP increase in the top RPM range. Check out the Softronic web site for the 987.1S or 987.2 models.

Apex1, just to add to your post, in California they do not test the exhaust , but they definitely do a detailed visual inspection. If any cats are missing you will fail.

Detailed visual inspection is subjective. Some shops are more stringent than others. The one benefit of the mid engine is that you can't just pop the hood. Most shops will plug into your ECU and look things over, collect their money and send you on your way.