[Polar Bear]

Hello all!

New BMW owner and new to this site, but I have a decent amount of experience modifying FI car and trucks.

I bought my alpine white 335is from a dealer who didn't seem like he knew what he had with 29k miles on the clock. He mentioned there were some modifications but didn't seem to have a full list. I have identified some pretty straightforward mods: ECS catch can, Active BOV/charge pipe, COBB exhaust. Now on my first cold start and drive, I noticed that the car has quite a strong exhaust smell so I stuck my arm/camera under the car today to see if I could ID if the car had the stock downpipes or aftermarket.

I see BMW places a nice cover under the engine bay so I could only get a peak, and without prior experience, I cannot tell if these are stock or not. What I can say is that if they are stock, BMW must have some tiny cats and they seem like they would have to be tucked pretty darn close to the turbos.

Any help would be appreciated in identifying these.

[RSL]

They are catless aftermarket. You can't miss stock cats, even with the lower cover on. If no CEL, something is installed: flash tune, old JB4 or DP fix to kill the codes.

Not sure how any dealer can legally sell a car without any factory emission equipment in place though. Dealers know exactly what they have, what they paid for it and what it's worth. If you got it for a song, they were looking to get rid of it.

[Polar Bear]

Originally Posted by RSL

They are catless aftermarket. You can't miss stock cats, even with the lower cover on. If no CEL, something is installed: flash tune, old JB4 or DP fix to kill the codes.

Not sure how any dealer can legally sell a car without any factory emission equipment in place though. Dealers know exactly what they have, what they paid for it and what it's worth. If you got it for a song, they were looking to get rid of it.

Yeah so that’s why I was kind of confused/torn on if the car had the stock DPs, cause I can’t imagine how they could sell it without emissions equipment. Not that I particularly care as I don’t get inspected and I had a cat delete on my last car, but it was something I chose.

How would I be able to tell if it has a flash?

The car was traded in at a Chevrolet dealer for a new Vette off the showroom floor. If they did know that would be a gamble not to say something knowing I would eventually find out.

[RSL]

Originally Posted by Polar Bear

Yeah so that’s why I was kind of confused/torn on if the car had the stock DPs, cause I can’t imagine how they could sell it without emissions equipment. Not that I particularly care as I don’t get inspected and I had a cat delete on my last car, but it was something I chose.

How would I be able to tell if it has a flash?

The car was traded in at a Chevrolet dealer for a new Vette off the showroom floor. If they did know that would be a gamble not to say something knowing I would eventually find out.

Pretty sure they'd be in trouble if you cared and brought it to their attention. They'd probably have to undo the sale or make it compliant.

Not sure there's anyway to tell if a flash is there without downloading the rom out of the DME except maybe verifying boost level and there's no quick way to do that. Either need to connect a mechanical boost gauge or get a datalogger. In general, if boost is a noticeable amount >8-10psi WOT without overboost (335is feature), probably a tune in there. Stock overboost would be in the 12-14psi range and, with a flash tune, there would probably be no difference in boost between overboost on/off.

If a JB4 is installed and active, the gauges likely sweep at start or you can try entering command mode...turn the ignition to run or start the car and push the volume and channel down buttons on the steering wheel simultaneously. The center dash screen would turn solid orange. JB4 is a piggyback and would physically be housed in the DME box under the hood. There could also be a JB4+flash, so you'd want to check for both if a JB4 is present. If the car is DCT, you really want a flash in there with a JB4.

If there's an MHD tune in there (popular), MHD app might identify it just connecting and reading the code screen. MHD is free to download and don't remember, but might be able to read the code screen without paying for anything, but you need an OBD-II + OTG cable to connect the device to the car.

If there is no flash, no JB4 (i.e. it is actually on a stock rom) and you have no CEL for cat efficiency, a DP fix is likely installed and would most likely be in the DME box under the hood also.

[Polar Bear]

Well thanks for that info, I have a lot of learning to do. I think I am beyond the point in my life where I feel the need to be catless so I’m going to call the dealer and see if we can work a deal out. Since I have the COBB exhaust on I think picking up their DPs is where I am headed.

I’ll search the forum for the DP fix details so i can scout it out

[RSL]

If they just did a readiness scan and there's a DP fix, the cat system will show ready even without cats. That's the whole point of the DP fix. Not that it changes anything, but easy to see how missing cats could go unnoticed without a physical inspection.

Verify there are actually no cats stuffed further up the DPs...maybe something super small or custom I've not seen before, but they look straight catless from what can be seen in the pics. There's really little room for anything further up the DPs and the smell is a dead giveaway, but be absolutely positive there are none before running back to the dealer with it. Pull the rear of the lower cover down and visually inspect the entire length of the pipes.

Cobb high flow catted are great, running mine over 4 years, no issues, no CEL on INA0S rom. For reference, stock DPs and Cobb for cat locations. You can see how far back the rear cats are on both and should easily be visible looking forward (my pic is front looking back with the cover off).

[Polar Bear]

Wow those COBB dps look like they are very well made and I can see that the cats seem to be in close proximity to the lower flange for both sets. The stock ones look like they have barrels for cats.

I will see if I can get further under the car tomorrow to see if I can make anything else out, or maybe a brand stamp. This car goes like a bat out of hell so I’m also kinda curious what numbers it would put down, I might dyno it before I make a swap to compare.

Appreciate all the help!

[Polar Bear]

I found this on a photo of the pipe, looks like a plate that says CUSTOM.

[Dmak]

https://cp-e.com/shop/product/bmw-n54-qkspl-downpipes/

Cpe down pipe?

[RSL]

Originally Posted by Polar Bear

Wow those COBB dps look like they are very well made and I can see that the cats seem to be in close proximity to the lower flange for both sets. The stock ones look like they have barrels for cats.

I will see if I can get further under the car tomorrow to see if I can make anything else out, or maybe a brand stamp. This car goes like a bat out of hell so I’m also kinda curious what numbers it would put down, I might dyno it before I make a swap to compare.

Appreciate all the help!

Guessing there's a tune in there, almost can't imagine there's not at this point. Depending what car you're coming from though, could be tough to tell seat of the pants. If MHD OTS tune, would be in the 360-390whp range on 93 and somewhat lower on 91, but it's all low end torque that you feel and mostly all the stock turbos are good for.

Stock 335is would put down somewhere around 300whp and the bolt-ons would barely make any difference in that. The tune dictates everything, bolt-ons are more or less just supporting mods on these cars. There will be no loss going from the catless to high flow catted.

The good news is, doesn't seem like the car was owned by a cheapskate. Cobb exhaust and CPE DPs are big money compared to the Chinesium stuff being sold. Would be a reasonable bet then, if there is a tune flashed in there, it's custom. Only thing better would be if there are upgraded turbos in there too Might want to give the car a thorough going through before confronting them in case they insist on cancelling the purchase...you might have gotten a monster deal if the car is otherwise right.

Originally Posted by Dmak

https://cp-e.com/shop/product/bmw-n54-qkspl-downpipes/

Cpe down pipe?

Yep, look like regular catless CPE. Here are their catted and the rear cat would be in the same spot, so would be easy to see if it is.

https://cp-e.com/shop/product/cp-e-q...ted-downpipes/

[Polar Bear]

Originally Posted by RSL

Guessing there's a tune in there, almost can't imagine there's not at this point. Depending what car you're coming from though, could be tough to tell seat of the pants. If MHD OTS tune, would be in the 360-390whp range on 93 and somewhat lower on 91, but it's all low end torque that you feel and mostly all the stock turbos are good for.

Stock 335is would put down somewhere around 300whp and the bolt-ons would barely make any difference in that. The tune dictates everything, bolt-ons are more or less just supporting mods on these cars. There will be no loss going from the catless to high flow catted.

The good news is, doesn't seem like the car was owned by a cheapskate. Cobb exhaust and CPE DPs are big money compared to the Chinesium stuff being sold. Would be a reasonable bet then, if there is a tune flashed in there, it's custom. Only thing better would be if there are upgraded turbos in there too Might want to give the car a thorough going through before confronting them in case they insist on cancelling the purchase...you might have gotten a monster deal if the car is otherwise right.

Yep, look like regular catless CPE. Here are their catted and the rear cat would be in the same spot, so would be easy to see if it is.

https://cp-e.com/shop/product/cp-e-q...ted-downpipes/

From what the salesman said after a week of talking about the car is the guy who owned it is rolling in cash and wanted an M3 but got this and then eventually paid cash for the vette, so the mods make sense I guess. I was originally just thrilled about a 2012 only having 29k miles

[Polar Bear]

Big help so far, this is why I love enthusiast forums.

[b92]

Welcome! Is your car 6MT or DCT? Also, any pics of the car?

As another user mentioned, try activating the JB4 menu via the steering wheel controls. If nothing happens then you should create a thread in the regional forum for Seattle to try and link up with someone that has an MHD device to see if the app can get a read. MHD is a free to download Android app, but I think you need to purchase a license within the app to do anything. I could be wrong here though.

[Polar Bear]

My car has the DCT in it and I don’t have any exterior pictures of it yet as it has been pouring here in the Seattle area since I got it delivered. I’m gonna wash it and get to know it better pretty soon. I’ll attach a shot of the engine bay.

I will try that check tonight and see if it yields anything, but I think I’m going to go full COBB Stage 3 with the tuner here shortly just so I know what’s all in it. Would I be able to sell those CPE pipes on here once I put the COBBs on?

RSL do the COBB highflow cats work well with reducing some of that noxious exhaust?

[RSL]

First start and maybe a couple heat cycles on new ones, you'll have the new cat/hot metal smell, but once that goes away, no smell with them, exhaust or otherwise. I have the stock mid-pipes with secondary cats, so can't say the Cobb exhaust will be entirely smell-free with no secondary cats, but could still be none and if not, it will definitely be a LOT less.

Volume-wise, they're pretty much as loud as catless, but help a lot keeping the exhaust a tone instead of noise. Cobb exhaust might sound alright with catless, but the catted will refine it.

Cobb is mostly out of the N54 game and has been for a while now, they haven't released any updated AP maps in some years. Not only that, in order to get the Access Tuner software from them now (which you need to create/adjust maps), you need to pay for and take a class before you can download it. So, at this point, it's either run old OTS maps they have, take the class to tune yourself or find an actual Cobb Protuner that still does N54s..and I think experienced ones are getting pretty hard to find. BQ is a Cobb Protuner and especially recommended for a DCT car, but not sure he's taking new business at this point.

Cobb AP is a solid flasher and their OTS maps are "OK", but I'd highly recommend MHD instead at this point. Whatever you go with, make sure to read and save the bin that's currently in the DME before flashing anything or it will be gone forever and you'll never be able to go back to it. Might wind up that it's a custom tune and way better than any OTS map you might try, so don't overwrite it without saving a copy first. Cobb AP will automatically save it and encrypt it on the AP when the "marriage" occurs, but with MHD, you need to manually save the existing rom first.

You can list the catless in the classifieds here.