To CAT or not to CAT, that is the question

[gojagz]

So, I am seeing several different options for DP's that are now becoming available. I have never modded a car to this level before, so this is all uncharted territory for me. I live in TX which has state emissions tests. From what I have heard/read a catless DP will make you fail. Ofcourse you MAY be able to go to some shaddy guy who is a friend of a friend that'll hook you up for a couple extra $$. I understand that. What is everyone's experience on going catless vs catted on emissions? Is it worth it to go catless and just change back to the stock DP once a year for the emissions test? How will that affect how the car runs for that day with the tune and other supporting mods? I basically just want to open a discussion on the topic because I know that more threads will start popping up about it as more options become available on the market. Cheers!

 

[airjor13]

No CAT for the win, cat-less DP is the best bang for the buck power mod you can do. Tree hugger's be damned. VA has emissions testing too......but not for every county

 

[CanadianST]

Personally I don't think switching out yearly is a viable option, it's not like changing the oil or anything, it's actually a fair amount of work. I have headers and a catless downpipe on one of my other cars and it would fail emissions as it sits but luckly I don't have any here, if it was a problem I probably wouldn't have them on my car but that's just me. Subbed though for further opinions.

 

[CanadianST]

No CAT for the win, cat-less DP is the best bang for the buck power mod you can do. Tree hugger's be damned. VA has emissions testing too......but not for every county

Did the catless DP trip a CEL? I'm looking into getting one in the future but would like to retain my warranty for a little while atleast .

 

[MOFiestaST]

I know its not the easiest like CanadianST said but they do sound awesome and the increase in power is there too so maybe just saving for a high flo cat might be a decent alternative. This is what I've done in the past but they weren't turbo cars which benefit from less restricted exhaust more than N/A cars.

 

[rodmoe]

The Cars I have had without cats to me just stunk like bad hydrocarbons i found it hard to tolerate . now we have no testing up here in Wi. so it is not a issue but I still went with the Hi Flo cat just cuz on the Dyno it was only 3 to 5 Hp less that the no cat..
From what I have heard (from Joe at 2J racing) once you get the factory cat out the swap isn't all that hard only thing is the O2 probes might need a little TLC to remove.. And I think some run a scrubber(can't think of the right word) or something on the rear O2 probe to fool the ECU into thinking it ok or the Cat is up to proper temp.. Some here have run the no cat pie and have a better feel for how it works with regard to the CEL. If you are worried about testing then go catted is my feeling if you want balls out best prefoemance go catless or do both $$$ and swap them.. on a side note I have yet to install mine so this is only my opionion with some good old hearsay mixed in.. hope it helps

 

[flurry]

I went the $$$ route and plan to swap as necessary. I was thinking catted all the way till I saw the 17 ft/lbs torque diff on the 2J Racing dyno.

 

[airjor13]

I plan on not running any de-fouler or O2 fooler. COBB said the rear post-cat O2 can dictate as much as 20% of fuel correction, really don't want to mess that up.

I probably will be getting a pro-tune or a modified OTS tune that disables the post-cat O2 so it doesn't trip the CEL.

 

[Colin1337]

I'll probably be switching to a catted downpipe if and when I move back to CA, but if I had my way I'd stay catless.

 

[rodmoe]

I plan on not running any de-fouler or O2 fooler. COBB said the rear post-cat O2 can dictate as much as 20% of fuel correction, really don't want to mess that up.

I probably will be getting a pro-tune or a modified OTS tune that disables the post-cat O2 so it doesn't trip the CEL.

Thats the word I was looking for Thanks

 

[Perry]

Catted for me. Not remotely worth the PITA swaps, cost, etc. Plus I get to feel all warm and fuzzy about myself for not ruining the planet like you guys!

 

[golfhack]

No cat for me. Won't have to put on the stock downpipe back on until October 2018.

 

[RyGuyFIST83]

I would like to go no cat but I never been in a car that doesn't have one,and with my weekly commute I'm wondering how bad/noticeable the smell would be. I prob won't even have the car longer than 5 years, as fast as I change cars(this one might be an exception) so not worried about testing. I don't even know n.j. Laws on no cat or cat .

I'm thinking ATP dp into a MRT exhaust. .........
Is the one there selling right now no cat? I really am loving the CPE "Nexus" downpipe/exhaust sound,and love how they made everything interchangeable,so if you wanna go straight pipe or add different tips,you can. Just might go with those guys. Tough decision...

-ry

 

[CanadianST]

I would like to go no cat but I never been in a car that doesn't have one,and with my weekly commute I'm wondering how bad/noticeable the smell would be. I prob won't even have the car longer than 5 years, as fast as I change cars(this one might be an exception) so not worried about testing. I don't even know n.j. Laws on no cat or cat .

I'm thinking ATP dp into a MRT exhaust. .........
Is the one there selling right now no cat? I really am loving the CPE "Nexus" downpipe/exhaust sound,and love how they made everything interchangeable,so if you wanna go straight pipe or add different tips,you can. Just might go with those guys. Tough decision...

-ry

The smell on my other car isn't overwhelming but it is noticable on startup especially. I don't find it a deal killer by any means though.

 

[XuperXero]

I've run catless on all my cars. O2 simulator (defouler as you guys called it) is MANDATORY. The number of people with modified cars running catless is barely enough to make a big impact on the environment(we are less than 1% of the cars on the road), so tree huggers can kiss my ass. The power gains alone is worth it.

However... since I'm in China and our car's cat is on the freaking manifold instead of exhaust system. I will be staying catted as they have one of the most stringent inspections here (attempt to battle the ever worsening smog here).

 

[Colin1337]

That really surprises me, you always hear about the air quality and how bad the pollution is over in China.

 

[mcummings182]

I am new as far as learning more about cars and mods. What is the difference between cat and de-cat?

 

[CanadianST]

I am new as far as learning more about cars and mods. What is the difference between cat and de-cat?

The "cat" is you still have a downpipe with the catalytic converter, de-cat is you've replaced the downpipe with one that does not have a "cat" or catalytic converter. It'll free up power but since a cat is an emissions control device in some places it is illegal to do a de-cat.

 

[XuperXero]

Any OEM intake and exhaust system for the car is made to meet environmental and noise standards. That being said. The OEM breathing system is like running a track and field while breathing through a straw.

 

[mcummings182]

If you get a downpipe with a cat back, will it fail the emissions check?