[nikg736]

I live in NC where apparently deleting secondary cats will cause you to fail inspection. Has anybody done a mod so they could swap the cats in for inspection and then swap out with straight pipes or resonators for regular driving?
I was actually thinking the easiest way to do this would be to make cuts in the straighter sections several inches away from the cats and just use exhaust clamps. Any thoughts?

[mike5124]

Supersprint makes bolt on second cat deletes I think for N52/N51, forgot what they're called.

First time I hear about a state caring about the secondary cats.

[Papa Popov]

If its just an OBD inspection you won't fail. Secondaries don't have O2 sensors and won't cause a CEL.

Visual inspection? Just gut the cats and weld them back in.

If they're testing the actual emissions, like the dude above said you can go with SS section 1 pipes. They bolt up to the headers and clamp on before the resonator. Should be able to swap 'em out pretty easily if you can get the rusty ass exhaust studs out from the manifold when initially removing them. They're not cheap, but its better than going to an exhaust shop that's gonna yop your cats if they cut them off. Those things are going for $300-500 these days.

If you're too lazy to swap out the pipes just ask around for the local enthusiast emissions guy if ya catch my drift.

[neilvan]

If you have a visual inspection then ya youll likely need it.

Best bet is to get some V-band clamps welded in and then get replacement ones(with clamps) that are straight pipe or have a resonator. V-bands are easy on and off and dont need gasket replacing.

Also the stock exhaust size up there is metric and the closest imperial is 2.125" which is an odd size

[nikg736]

Thanks for all the feedback so far.

*Just Gut The Cats -- I thought about this, but decided maybe not for a few reasons. First, what if I hate something about no cats? Smell. Sound. Whatever. If they are intact then I can just swap them back in. Second, and I don't know if there is any truth to this, I had read that gutted cats interfere with exhaust flow and may even have a negative affect on performance whereas straight pipe or resonator would not. I certainly don't want a drop in performance as the 328i is not necessarily a missile to begin with.

*Inspection - I honestly have no idea if there is a visual, but a few posts from other NC members seems to suggest that there is. No visual, no problem. Otherwise, another reason to make things "swappable"

I have a MIG welder and I am capable enough to pull off some basic exhaust work (even if it might look like crap, it will be solid). So, it sounds like the "easiest" way to accomplish the swap is cut out the cat section and use v-clamps to swap in some straight pipes.

Any thoughts on resonators with cat delete options?
1- delete cats, straight pipes in their place, keep stock resonator
2- delete cats, vibrant resonators in their place, keep stock resonator
3- delete cats, straight pipes in their place, vibrant resonator to replace stock resonator (with addition of y-pipe)
4- delete cats, vibrants in their place and vibrant in place of stock resonator


The goal is an exhaust that gives some pops/crackles/sound without annoying drone.
I already replaced the stock muffler with a Magnaflow

Thanks

[nikg736]

I found this information below on a few different sites. It boggles my mind, because there are tons of truck around here that sound like they are running straight pipes (and sound like total loud crap in my opinion). However, it seems to re-affirm the visual inspection in NC. I think they will even fail you for a muffler delete or exhaust cutout.


What does a North Carolina emissions inspection consist of? [Back to Top]
A North Carolina emissions inspection consists of connecting a certified analyzer to the vehicle's OBDII system to verify that all vehicle emissions components/systems are working per the manufacturer specifications along with a visual safety/tamper inspection.


While NC emissions inspections are relatively new, exhaust system checks have been around for years as a part of the annual inspection. This car inspection step checks for removed, broken, tampered, or disconnected exhaust system parts and emissions control devices. Depending on your vehicle, this can include your catalytic converter, muffler, exhaust pipe, air pump system, EGR valve, PCV valve, and oxygen sensor, among others.

It used to be common for drivers to tamper with these devices in an attempt to improve vehicle speed and performance. This practice has become much less popular over the years, so this check will likely only cause you to fail your car inspection if an element of your exhaust system is failing. However, if you do choose to tamper with your emissions control devices, it could earn you a $250 fine in addition to a car inspection failure.

[nikg736]

Any thoughts on resonators with cat delete options?
1- delete cats, straight pipes in their place, keep stock resonator
2- delete cats, vibrant resonators in their place, keep stock resonator
3- delete cats, straight pipes in their place, vibrant resonator to replace stock resonator (with addition of y-pipe)
4- delete cats, vibrants in their place and vibrant in place of stock resonator


The goal is an exhaust that gives some pops/crackles/sound without annoying drone. I am leaning towards option #3.
I already replaced the stock muffler with a Magnaflow

[850CSi]

I was under the impression that removing or gutting the secondary cats didn’t make much of a difference in our cars but I’m happy to be told I’m mistaken in that regard.

[nikg736]

Yeah...I'm not sure if it will really lead to a performance increase. The goal is to basically get some better sound and at the very least not take away from performance.

[rothwem]

I live in NC, and have for the last 17 years. Nobody has ever done a visual inspection under my car. Is the OP's thread in response to a failed inspection? They check OBD2 and headlights, windshield wipers, brake lights, turn signals, etc.

Pro-tip: the inspection costs the same whether it's at Jose's gas and go or the BMW dealership, so go to the fanciest BMW dealership you know of and get yourself a latte and a scone to go with your inspection.

[Papa Popov]

Originally Posted by nikg736

Any thoughts on resonators with cat delete options?
1- delete cats, straight pipes in their place, keep stock resonator
2- delete cats, vibrant resonators in their place, keep stock resonator
3- delete cats, straight pipes in their place, vibrant resonator to replace stock resonator (with addition of y-pipe)
4- delete cats, vibrants in their place and vibrant in place of stock resonator


The goal is an exhaust that gives some pops/crackles/sound without annoying drone. I am leaning towards option #3.
I already replaced the stock muffler with a Magnaflow

I still have my secondaries but I swapped my muffler for a Vibrant ultraquiet resonator and love the sound. I'd keep the stock resonator in place, all of the cars I've heard without it (deleted or swapped for something else) sound awful.