[fistofsouth]

OK so I know that in most instances when it comes to OBD II Compliant State Emissions Testing the inspector simply looks for current error codes on the emissions system. So long as you don't have a CEL/ DTC (Diagnostic Trouble Code) or a system that is in "Not Ready" status you will pass you emissions test.

So I have BMW 335i (N54 E92) and would like to get new downpipes and a custom exhaust with a Bastuck Quad Exhaust. That being the case I have a few questions for those that might know (I've searched already, some topics are close, but no cigar) :

1. For those with Downpipes what influence does that have on your emissions test? In most instances the cat is removed right? Does that throw a CEL or DTC?

2. Same question for those with cat-back exhausts either pre-fab or custom, what influence does it have on your state inspection? Do you throw a CEL/ DTC?

3. For a custom system are there race-cats or free-flow cats that can be used for the 335i? If so does anyone have any experience with emissions testing using them? If not why not? Are the stock cats adequate for performance applications? I'm just looking to remove as many restrictions as possible, but I want to pass inspection.

[gatorheel]

I can speak to the downpipes. Catless with throw a CEL which can be remedied for ODBII inspection by installing BMS Downpipe fix. Note that this is NOT included in JB4 and that it is a separate product that you must buy. This allows your ECU to go back to "emissions ready" state for ODBII inspection.

Re: cats for custom exhaust, I know they are out there, just dont remember who makes them. i think people typically put them at midpipe level.

Re: exhaust, no knowledge. sorry.

[fistofsouth]

Thanks nelsonmg.

[idrift4wd]

Originally Posted by fistofsouth

1. For those with Downpipes what influence does that have on your emissions test? In most instances the cat is removed right? Does that throw a CEL or DTC?

2. Same question for those with cat-back exhausts either pre-fab or custom, what influence does it have on your state inspection? Do you throw a CEL/ DTC?

3. For a custom system are there race-cats or free-flow cats that can be used for the 335i? If so does anyone have any experience with emissions testing using them? If not why not? Are the stock cats adequate for performance applications? I'm just looking to remove as many restrictions as possible, but I want to pass inspection.

1. like someone said, you need a DP fix to get your car ready for OBDII test.

2.no lights will be thrown for exhaust work after the downpipe.

3. There are high-flow cat dp available which should work (add a few HP) and not throw a CEL. Stock cats are decent, many still run stock dp on their tuned cars.

I would just run stock dp if i were you. if you're not happy, then go catless (with a DP fix). Downpipes are really your only main restriction. you may like your 2nd cat delete, but you wont gain much if anything.

[carlsontheflyer]

I own an emission testing station in Atlanta, Georgia.

Here, even if you have a DP fix installed that doesn't trigger a CEL with a P0420 and P0430 codes (Catalyst Efficiency Below Threshold), which is another way of saying your cats have failed or do not exist, your car will not pass the emission test. Due to availability of devices that fool the ECU into not throwing code, in Georgia emission inspectors are required to visually verify the presence of catalytic converters, and in the process of the performing OBDII test, the emission analyzer actually asks a question on one of the screens whether the catalytic converters are present. If the answer is NO, the computer will fail the vehicle.

I am pretty sure that in Texas the rules are the same. So, unless the inspector does't check if your car actually has cats, or your downpipes or midpipes look like they have something resembling a cat (), you may have a problem.

P.S. This is the main reason I will upgrade to downpipes with high flow cats on them, even though it will be considerably more expensive. I'll just be a hypocrite if I drive around without catalytic converters, while at the same time not allowing others to do the same.

[Wedge1967]

If you go with catless DPs, I would recommend running secondary cats due to the fact the turbos smoke and the smell from catless exhaust is awful. I cut my secondary cats out and it was the worst mistake I make and now I'm in the process of putting them back on. Even with visual, if you have the secondary cats, the inspector is not going to fail your vehical for not having primary cats because they are impossible to see. Just get the O2 shim to make sure your car is in ready state.

[fistofsouth]

Thanks idrift4wd

Thanks also to carlsontheflyer

carlsontheflyer please understand that essentially I want to have at least one set of cats, but ideally I would like a full 3 inch system WITH high-flow-cats that will also not throw a CEL/ DTC. So something that would pass an ODBII AND Visual inspection. I want the cats I just don't want them to be restrictive even if the stock cats are good.

The thing s all DPs and exhaust systems for the E92/ N54 seem to have at least a 2.5 inch flange ( and thus 2.5 inch restriction) somewhere in the system. Got a 3 inch DP? great, but the flange is 2.5 inches to connect to a stock exhaust. 2.75 inch cat-back exhaust? great, but it still needs a 2.5 inch connector. See what I mean? Correct me if I'm wrong, but there is no full system that is larger and less restrictive than stock at EVERY point.

[napeHbNYC]

Does COBB need dp fix or it is sufficient by itself to pass inspection?

[DallasBoosted]

Originally Posted by napeHbNYC

Does COBB need dp fix or it is sufficient by itself to pass inspection?

Needs DP fix

[carlsontheflyer]

Originally Posted by fistofsouth

Thanks idrift4wd

Thanks also to carlsontheflyer

carlsontheflyer please understand that essentially I want to have at least one set of cats, but ideally I would like a full 3 inch system WITH high-flow-cats that will also not throw a CEL/ DTC. So something that would pass an ODBII AND Visual inspection. I want the cats I just don't want them to be restrictive even if the stock cats are good.

The thing s all DPs and exhaust systems for the E92/ N54 seem to have at least a 2.5 inch flange ( and thus 2.5 inch restriction) somewhere in the system. Got a 3 inch DP? great, but the flange is 2.5 inches to connect to a stock exhaust. 2.75 inch cat-back exhaust? great, but it still needs a 2.5 inch connector. See what I mean? Correct me if I'm wrong, but there is no full system that is larger and less restrictive than stock at EVERY point.

Someone will correct me if I am wrong here, but the biggest restriction in the entire exhaust system is the catalytic converters, and not the 2.5 inch flange. Installing downpipes with high flow cats, like the ones from CP-E, for example, will make all the difference you are looking for. Look at BuraQ's car. With a good tune, FMIC, DCI, high flow cats, and no meth he runs in the 11.7's 1/4 mile in his 335is.

[napeHbNYC]

^^ are there dyno comparisons of cattles vs high flow cats with the same setup?

[carlsontheflyer]

Originally Posted by Wedge1967

If you go with catless DPs, I would recommend running secondary cats due to the fact the turbos smoke and the smell from catless exhaust is awful. I cut my secondary cats out and it was the worst mistake I make and now I'm in the process of putting them back on. Even with visual, if you have the secondary cats, the inspector is not going to fail your vehical for not having primary cats because they are impossible to see. Just get the O2 shim to make sure your car is in ready state.

Ummmm... if you look on the left side of the engine with enough light, you can easily see the primary catalytic converters (or lack of them).

[gatorheel]

found the info on the aftermarket cats for custom applications:

100 HJS Cats

HJS Emissions Technology

there was talk about welding these into midpipes...

[brusk]

I live outside of Dallas and mine passed while using Cobb Stage 2+ and no cats. I don't know if it helped but i found a local oil change place near me where there were a few sporty cars in the employee section in the hopes that knowing they are car guys they might let it slide. According to the sheet everything was good on the tests.

[MrRager]

Originally Posted by fistofsouth

OK so I know that in most instances when it comes to OBD II Compliant State Emissions Testing the inspector simply looks for current error codes on the emissions system. So long as you don't have a CEL/ DTC (Diagnostic Trouble Code) or a system that is in "Not Ready" status you will pass you emissions test.

So I have BMW 335i (N54 E92) and would like to get new downpipes and a custom exhaust with a Bastuck Quad Exhaust. That being the case I have a few questions for those that might know (I've searched already, some topics are close, but no cigar) :

1. For those with Downpipes what influence does that have on your emissions test? In most instances the cat is removed right? Does that throw a CEL or DTC?

2. Same question for those with cat-back exhausts either pre-fab or custom, what influence does it have on your state inspection? Do you throw a CEL/ DTC?

3. For a custom system are there race-cats or free-flow cats that can be used for the 335i? If so does anyone have any experience with emissions testing using them? If not why not? Are the stock cats adequate for performance applications? I'm just looking to remove as many restrictions as possible, but I want to pass inspection.

most places in texas will pass you if your check engine light is not on. some may look under your car for cats. but they will think that your resonators are cats if you have stock exhaust but catless downpipes.

[Wedge1967]

Originally Posted by carlsontheflyer

Ummmm... if you look on the left side of the engine with enough light, you can easily see the primary catalytic converters (or lack of them).

Well, I don't know how GA does emissions testing but in OR, they do a walk about for noise, smoke, and smell. If you have secondaries and you pass OBD, why would they open the hood or take the time to do a visual inspection?

I'm not saying you're wrong... Just never seen a tester go to the trouble of a full visual. In OR it's a pass or fail based on OBD. Unless your exhaust smells like @$$ and you have boy racer fart cans.

[carlsontheflyer]

Originally Posted by Wedge1967

Well, I don't know how GA does emissions testing but in OR, they do a walk about for noise, smoke, and smell. If you have secondaries and you pass OBD, why would they open the hood or take the time to do a visual inspection?

I'm not saying you're wrong... Just never seen a tester go to the trouble of a full visual. In OR it's a pass or fail based on OBD. Unless your exhaust smells like @$$ and you have boy racer fart cans.

In Georgia it's the law. Inspectors MUST perform a visual inspection. for cats. The EPA sends in "mystery shoppers" at least a couple of times a year who watch and report. Only cars that get a "pass" on that are the ones where cats are hidden by the underbody (Ferrari, Lamborghini, etc.) or integrated into side exhaust (Viper, Ford GT, etc). We do not go by exhaust smell.

[Wedge1967]

Originally Posted by carlsontheflyer

In Georgia it's the law. Inspectors MUST perform a visual inspection. for cats. The EPA sends in "mystery shoppers" at least a couple of times a year who watch and report. Only cars that get a "pass" on that are the ones where cats are hidden by the underbody (Ferrari, Lamborghini, etc.) or integrated into side exhaust (Viper, Ford GT, etc). We do not go by exhaust smell.

Good thing I don't live in GA anymore.

[E92murdered]

in california i heard they stopped the sniffer test is that true? i am due for smog in july, in addition OP does your state require a sniffer test? that will be an automatic fail.

[ken1137]

AR design has race cats, pricey but they are excellent quality. I still needed the BMS DP fix b/c I am running GIAC Stage II.

[falconey]

Originally Posted by carlsontheflyer

I own an emission testing station in Atlanta, Georgia.

Here, even if you have a DP fix installed that doesn't trigger a CEL with a P0420 and P0430 codes (Catalyst Efficiency Below Threshold), which is another way of saying your cats have failed or do not exist, your car will not pass the emission test. Due to availability of devices that fool the ECU into not throwing code, in Georgia emission inspectors are required to visually verify the presence of catalytic converters, and in the process of the performing OBDII test, the emission analyzer actually asks a question on one of the screens whether the catalytic converters are present. If the answer is NO, the computer will fail the vehicle.

I am pretty sure that in Texas the rules are the same. So, unless the inspector does't check if your car actually has cats, or your downpipes or midpipes look like they have something resembling a cat (), you may have a problem.

P.S. This is the main reason I will upgrade to downpipes with high flow cats on them, even though it will be considerably more expensive. I'll just be a hypocrite if I drive around without catalytic converters, while at the same time not allowing others to do the same.

I'm in Atlanta and I had zero issues passing an emissions test with the downpipe fix. Inspector didn't even look at the cats, but you shouldn't be failed if you keep the secondary cats which aren't deleted with catless downpipes anyway.

[fistofsouth]

Thanks for all the replies.

Does anyone know if the CP-E with cats is a full 3 inch pipe? Meaning are the flanges on both ends 3 inches? IF the exhaust side flange is less than 3 inches I'm back to square one. Although I guess a good custom exhaust shop could cut the DPs and weld the directly to a 3 inch custom exhaust.

In the end I see little point in upgrading my exhaust (beyond sound) if I can't get larger than stock throughout the system. Like I said before 3 inch DPs with a 2.75 inch cat-back still face a bottleneck when the connector between the two is stock diameter.