Catted vs catless DP

[runnerlk]

I'm a newbie to the mods and looking to run a map that requires a down pipe. I have heard a lot of negative things about catted DPs that they really don't work long term and wondered if I run a catless DP what can I do to overcome the check engine light when it comes time for inspection?
I'm in NC if that makes a difference I know each state is different.

[darkrom]

Catted downpipes are 100% pointless. Go catless.

Be sure you understand how to pass emissions since either catless or "high flow" catted downpipes WILL cause you to fail emissions if you just slap them on and bring it in.

How is emissions done in your state? Do they stick a probe in the exhaust and "sniffer" it, or do they plug in to your OBD-II port and run a check that way? I can help you pass emissions in most cases or give correct advice on the subject.


There is a LOT of misinformation about people "passing" with just JB4 or Cobb. Neither of those alone will actually let you pass emissions, all they do is keep the CEL away to not annoy the driver.

To be clear, getting rid of the CEL is as simple as running JB4 or Cobb. Passing emissions...EVEN WITHOUT THE CEL requires extra steps.

[runnerlk]

Originally Posted by darkrom

Catted downpipes are 100% pointless. Go catless.

Be sure you understand how to pass emissions since either catless or "high flow" catted downpipes WILL cause you to fail emissions if you just slap them on and bring it in.

How is emissions done in your state? Do they stick a probe in the exhaust and "sniffer" it, or do they plug in to your OBD-II port and run a check that way? I can help you pass emissions in most cases or give correct advice on the subject.


There is a LOT of misinformation about people "passing" with just JB4 or Cobb. Neither of those alone will actually let you pass emissions, all they do is keep the CEL away to not annoy the driver.

To be clear, getting rid of the CEL is as simple as running JB4 or Cobb. Passing emissions...EVEN WITHOUT THE CEL requires extra steps.

darkrom thanks for the info. Here is a statement from the NCDOT website regarding emissions in NC.

On-Board Diagnostic (OBD) Emissions Inspection

"North Carolina is fighting ozone-forming emissions from gasoline-operated cars and light duty trucks. Inspections are conducted using the vehicle’s On-Board Diagnostic (OBD) system, computerized equipment installed on all new vehicles since 1996."

[lowbudgethero]

Depends if there is a sniffer test or if you just have to pass OBD. On other cars that I've had in NJ, a catted 3 inch downpipe worked fine and has passed inspection every year. Most cars that are lower in displacement can pass emissions when warmed up without any catalytic converter.

[runnerlk]

in NC they plug into the OBD

[darkrom]

Ok so you have an OBD test. Hit up Mike from X-PH and get the "x-kitty" from him.

So with cobb you won't see the CEL in the car when you go catless. That is to not annoy you.

The X-kitty can be installed to pass emissions if they only use the OBDII scanner.


There are ZERO benefits to a catted downpipe since you won't pass emissions with either (unless you use x-kitty). Might as well get the most power.

[lowbudgethero]

Originally Posted by darkrom

Ok so you have an OBD test. Hit up Mike from X-PH and get the "x-kitty" from him.

So with cobb you won't see the CEL in the car when you go catless. That is to not annoy you.

The X-kitty can be installed to pass emissions if they only use the OBDII scanner.


There are ZERO benefits to a catted downpipe since you won't pass emissions with either (unless you use x-kitty). Might as well get the most power.

Just to add, if you retain the stock exhaust with down pipes the secondary catalytic converters are enough to pass a sniffer test in many parts of the US.

[runnerlk]

X-kitty only works on N54? mine is N55

[vivanapoli806]

Originally Posted by runnerlk

X-kitty only works on N54? mine is N55

There is no dp fix for the n55 so ur car will not be in the ready state to pass emissions

[BMWX1-35i]

I'm not sure I agree with this statement. "Catted downpipes are 100% pointless".. Catted DP have their place and they do make more HP, not as much as catless of course BUT, they do work. If your in a state that also does a visual inspection, you need them.

[darkrom]

Originally Posted by 135droptop

I'm not sure I agree with this statement. "Catted downpipes are 100% pointless".. Catted DP have their place and they do make more HP, not as much as catless of course BUT, they do work. If your in a state that also does a visual inspection, you need them.

If they do a visual inspection can't they tell a "high flow" cat isn't OEM? Can't they smell/sniff/plug to find out that you are still not going to pass?

[Ski Killset]

I'm going to disagree with catted being 100% pointless as well. My last car made 8ftlbs more wtq with a cat than without. Lost only 2 whp. This was on a turbo four cylinder so 8ftlbs was a considerable and noticable gain.

I have a set of catless DPs that I am going to sell. I this modern world there is no reason you shouldn't be able to make 400hp and be emissions legal as well. I have the BMS downpipe fix and all that too but in the end I just prefer being legal. With more torque.

[Ski Killset]

Originally Posted by darkrom

If they do a visual inspection can't they tell a "high flow" cat isn't OEM? Can't they smell/sniff/plug to find out that you are still not going to pass?

In all states except California, aftermarket cats are allowed as replacements. It's up to the OBD2 system to determine if they are working or not.

[runnerlk]

in speaking to the shop that I go to. they do a visual inspection to validate the presence of cats along with the OBD plug in. they do not care if it is OEM or not. so I think I will go with the Cobb high flow catted dp.

[mike@x-ph.com]

go catless

[darkrom]

Originally Posted by Ski Killset

In all states except California, aftermarket cats are allowed as replacements. It's up to the OBD2 system to determine if they are working or not.

Ok but they can't be "high flow" cats. As in they have to be as bad as the OEM cats in the first place. If they are flowing more, they are emitting more. If that were the case why not strap a fake cat "shell" over a catless downpipe and say "its an aftermarket cat"?

They still actually test emissions, unless some states literally just look at your downpipe and say "I see a cat it is all good" but I don't believe most states are like that.

[darkrom]

IMO full catless or OEM dps. I myself run stock DPs to simply not deal with the fumes since I've deleted my secondary cats. The fumes really bothered me on my catless evo, this car should be even worse. If I was going to spend the money I'd want actual gains for such a bitch of a part to install.

[edisapimp]

Doesn't anyone just slip the kid a $20 bill before the inspection to make things go more smoothly? Or is that just me...

[runnerlk]

Originally Posted by darkrom

Ok but they can't be "high flow" cats. As in they have to be as bad as the OEM cats in the first place. If they are flowing more, they are emitting more. If that were the case why not strap a fake cat "shell" over a catless downpipe and say "its an aftermarket cat"?

They still actually test emissions, unless some states literally just look at your downpipe and say "I see a cat it is all good" but I don't believe most states are like that.

Isn't the only way to test emmisions to do a sniff test? I spoke to the BMW dealer that does my inspections and was told that they do the OBD....I guess for CEL and a visual.

Cobb has told me they have had no issues with inspections in any state other than CA and offer a full refund if it doesn't pass which I will know right away since the installer is also my inspection station.

I fully understand Mike that catless is the way to go but I'm not tracking the car so I am willing to give up some gains and not have to deal with the aggrivation of switching between OEM and catless every year for inspection.

Now we get the X-Kitty for N55 I may rethink.

[darkrom]

Originally Posted by runnerlk

Isn't the only way to test emmisions to do a sniff test? I spoke to the BMW dealer that does my inspections and was told that they do the OBD....I guess for CEL and a visual.

Cobb has told me they have had no issues with inspections in any state other than CA and offer a full refund if it doesn't pass which I will know right away since the installer is also my inspection station.

I fully understand Mike that catless is the way to go but I'm not tracking the car so I am willing to give up some gains and not have to deal with the aggrivation of switching between OEM and catless every year for inspection.

Now we get the X-Kitty for N55 I may rethink.

Got any more info on that cobb catted DP? If they guarantee it will pass, it must be the same cell count as the OEM cat, or VERY close. Not doubting you, but you brought up the first interesting thing I've heard about catted downpipes. Lets say the factory DP is 300 cell, if the cobb is 300 cell it will pass, but its also not going to actually add much power at all, if any.

[Ski Killset]

Originally Posted by darkrom

Ok but they can't be "high flow" cats. As in they have to be as bad as the OEM cats in the first place. If they are flowing more, they are emitting more. If that were the case why not strap a fake cat "shell" over a catless downpipe and say "its an aftermarket cat"?

They still actually test emissions, unless some states literally just look at your downpipe and say "I see a cat it is all good" but I don't believe most states are like that.

They only have to meet or exceed the performance of the OE cat. So if it doesn't trigger a code, it is working. I took my car through DEQ here four times woth a high flow cat on it that didn't trigger a code and it passed. The car originally had two low efficiency cats, now one high flow cat and the OBD was happy so the DEQ was happy. Most high flow cats a tually out perform OE cats in fliw and actual catalytic performance. They will clean up more.