This may be a dumb question but i would like to know/learn. What are the reasons for Cats?? pros/cons also?

 

Matt - I appreciate all the effort you've put into finding the perfect exhaust. I did the TPC side bypass that preserves the valves but didn't change the headers or remove the cats. It will be interesting to compare these two options at the Smokies event. My drone is gone and my valve transition is also more subdued as well. I'm sure I'm not making as much power as the Dundon setup but I'm surprised you're not more concerned about running catless. It is against the law and your videos certainly get lots of attention. Seems like a real risk. I'm curious why aren't you more concerned about that?

 

Matt awersome set up... Looking forward for the review.

 

Yes....disclaimer.....like most mfr use........ This exhaust system is for "track use only"

 

Great videos as always. I love this set up but I'm worried about warranty if I have a issue. I guess if you took the car into service for anything you could change them back. A big pain to do so. Also I live in a state where we have emissions test so I would have to switch it back for that every year. Been there done that on a Mustang in the 90s.
I still can't wait to hear this in person, just worried I might want it enough to deal with the above.

 

Cats = Catalytic converters. A catalytic converter is an emissions control device that converts toxic pollutants in exhaust gas to less toxic pollutants.

Replacing the cats with straight pipes allows the exhaust gases to flow more freely and straight pipes weigh much lass than cats. On the 991s, the cats are integral with the headers. Cats can't be changed or eliminated without also changing the headers. On the 996s and 997s, the cats were separate from the headers.

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Yes, this is a RACE EXHAUST for off road use only it is not street legal by the letter of the law.

One option I will bring up is that we have the ability to Clone the stock DME and make another one and with the new DME we can flash the tune on that ecu as well and make sure the CEL never does come on at all. Then if you had to take it to the dealer you could un bolt and swap out the DME plug and play and the car will start right up no problem. The mileage and hours are stored in the cluster not the DME so all that does get saved there. Currently DME's are fairly cheap like around $1100 so that new DME plus the clone and flash may only be $2-3000. Just another option.

Something else we are looking into is the MAP for the EXHAUST flap button. going to try to see if we can change the program so that when you hit the flap button it is on all the time.

 

Now, this is what I would be interested in. Immensely.

Please keep up the good work, and thank you for your efforts thus far.

 

Based on my experience running catless on my Akrapovic M3 system, this catless system is not going to last long on Matt's GT3. His need for constant cleanliness will not accept the additional soot that a catless system produces.

 

With my advancing age, and having dedicated race and track cars, I keep the catalysts. Modern high flow cats ar light, relatively inexpensive and cost almost nothing on the dyno. There is IMO no excuse not to run cats on a car that is primarily street. You don't need the tiny power increase and you aren't racing. And the pontificating part of me says if everyone thought they were above the law the skies would be like China and India.

 

Agreed 100%.

 

You definitely have a point.

 

It is mostly fitment and cost to build the system to make the same power and cost remain in the same ballpark.

However I am working on a carted version as well. Just need to try to make it all work.

 

Let's see a cat'd version where the cats are simply right after the long tube headers, and of course, this would get rid of the OEM center muffler. Could it be designed to then just simply add or remove the Cat section for the OEM center muffler??

 

Is there an option with the Dundon system to just get a side muffler delete while keeping stock headers/cats and stock center muffler? Other that saving a few pounds and maybe increasing noise, is it even worth it?