What midpipes to get

[csmith7393]

I have an afe cat back with stock midpipes and dp. I was wondering what midpipes i should get, resonated or non resonated. And what would the difference in sound be for resonated as compared to non resonated midpipes.
-thanks

[randomquickness]

Berk Technology can hook you up...check out sound clips on youtube as well.

[1speedbike]

I love my Berk Midpipes. I know Mad Dad also makes similar ones, but honestly I feel like all midpipes will be very similar, and I bought these together with the axleback. You can't go wrong either way. The resonators in the Berk ones don't let the loudness get too out of control, but the sound is very throaty and deep on lower RPMs, and kind of exotic sounding when you really hit it (especially in conjunction with the Berk axleback (or any good quality axleback) and the turbo whine really sounding out with a DCI). Without resonators you might be getting into "obnoxiously loud" territory without adding any throatiness to the sound. With the current set up my car is loud enough to hear it coming into my development (and my house is way at the back) when I really hit it, but with a soft foot I can pass by cops no problem, it doesn't emit any more sound than a big pickup truck normally does while on a light throttle.

This is my car with the Berk midpipes and axleback:

(for some reason it's not letting me embed the video, sorry!)

[oman135]

cp-e!

[philiopf22]

sorry to do this, but I'll hijack the thread anyway. Woudl it be rediculous to run AR kittyless with the secondary cats in place to the BMW PE? My understanding is that the majority of the restriction is on the front CATS. I'm also hoping that the mid cats will muffle the sound a bit so it isn't too loud.

[1speedbike]

Originally Posted by philiopf22

sorry to do this, but I'll hijack the thread anyway. Woudl it be rediculous to run AR kittyless with the secondary cats in place to the BMW PE? My understanding is that the majority of the restriction is on the front CATS. I'm also hoping that the mid cats will muffle the sound a bit so it isn't too loud.

the secondary cats don't do much at all. if you take them out, you're still street legal. That's how little they do, the primary cats are the ones doing everything; the secondaries don't even exist on N55 cars. They're also restrictive, though not really all that restrictive compared to the primaries.

But if you're willing to take your primary cats out, thus making your car street-illegal, you really might as well swap the midpipes as well and just get resonated midpipes. The resonated ones make your car slightly louder (not much, MUCH louder) while still creating a deeper, more exotic sound, and allowing for easier breathing.

But keeping the cats in there really won't do that much. You'll still be street-illegal. If money's your only concern then keep them, but you really might as well just swap them out as well from an emissions point of view :P That's my opinion at least.

[The1]

Originally Posted by 1speedbike

the secondary cats don't do much at all. if you take them out, you're still street legal. That's how little they do, the primary cats are the ones doing everything; the secondaries don't even exist on N55 cars. They're also restrictive, though not really all that restrictive compared to the primaries.

But if you're willing to take your primary cats out, thus making your car street-illegal, you really might as well swap the midpipes as well and just get resonated midpipes. The resonated ones make your car slightly louder (not much, MUCH louder) while still creating a deeper, more exotic sound, and allowing for easier breathing.

But keeping the cats in there really won't do that much. You'll still be street-illegal. If money's your only concern then keep them, but you really might as well just swap them out as well from an emissions point of view :P That's my opinion at least.

check your local laws before doing this....

where i am, they can probe your exhaust to see if you have a cat installed at all. so if you go catless, there will be nothing to stop the probe from moving. Also if they do this, they will probably do a visible inspection too, so if they see a cat and feel a cat, you might get away with it.

I'm not sure how much of a problem it is for most of the states, but here in canada, they can pull people over at the side of the road.

I plan to keep a cat in. I removed it from my last car, and i drove around scared all the time.

I will likely install High Flow cats in place of the secondary units. probably won't do much of anything, but at least there's something there, and it will keep smells down once they are warmed up enough.

[dcho]

i've got berk mids. they fit and sound great!

[Toker335i]

what happen if you get caught without primary or secondary cats in California?

[1speedbike]

Originally Posted by The1

check your local laws before doing this....

Definitely. the point i was trying to make (but i didn't phrase it very eloquently) was that if the OP wants to take our his primary cats anyway, there's no real point to having the secondary cats. they don't do enough emissions-wise to think that keeping them while deleting the primaries will keep you safe from getting in trouble. and while they're not AS restrictive as the primaries, they're still restricting the flow, so the only reason NOT to upgrade the midpipes (in my opinion) if you're already getting catless DP's is to save money, and shouldn't be for the sake of emissions or noise.

Originally Posted by Toker335i

what happen if you get caught without primary or secondary cats in California?

It's up to the cop, but if he pulls you over for something else (loud exhaust, speeding, etc) and smells that you're catless, he can impound your vehicle, fine you, etc. Also if your neighbors hate you they can file specific complains for a "smoking" or "smelly" vehicle to notify the police for you.

[BerkTechnology]

Million dollar question: Has anyone actually cut open the OEM midpipe to verify that those are secondary cats? I would like to make an official $5 bet that they are just resonators.

Or are there any plumbers here that can take a borescope and look inside the OEM midpipe?

[1speedbike]

Originally Posted by BerkTechnology

Million dollar question: Has anyone actually cut open the OEM midpipe to verify that those are secondary cats? I would like to make an official $5 bet that they are just resonators.

Or are there any plumbers here that can take a borescope and look inside the OEM midpipe?

http://realoem.com/bmw/showparts.do?...70&hg=18&fg=10



E82 135i Catalytic converter/Front silencer



No.DescriptionSupplementQty From Up To Part NumberPriceNotes01Rmfd catalyst with muffler
1

18307559994$2,170.94


jesus tap-dancing christ, i have $2000+ dollars sitting around in my garage. wonder how much the primary cats are worth

EDIT: in case anyone's wondering, 957 bucks each :P

[BerkTechnology]

Damn, so does this mean I owe you $5 now? Or do i have to cut up a midpipe to clear my name?

[onefastman]

Cut up that mid and do some testing

[1speedbike]

Originally Posted by BerkTechnology

Damn, so does this mean I owe you $5 now? Or do i have to cut up a midpipe to clear my name?

Hahahaha no $5 required, just keep making awesome stuff.

if you end up actually cutting them and find that there's no cats, BMW will really have to do some explaining as to why they charge 2k for resonators

[TZANIDO777]

http://www.shopicarbon.com/ProductDe...-E82-Exh-Stg-0

Does anybody know anything about these midpipes from icarbon??

[BerkTechnology]

The exhaust system as a whole will sound a lot smoother if you have resonated midpipes vs. non-resonated. The resonators mellow out the system for for a smoother overall tone.

You can see the two resonators in our system in this pic.

[E92White]

if the stock midpipes are just resonators,in terms of restriction,does it really matter then if you cut them off ? If they are just resonators,I would think the gains would be minimal compared to catless downpipes,or even a cat-back exhaust.

[BerkTechnology]

I cut up an OEM N54 midpipe and they are indeed two cats in there. They are not resonators.

So our midpipes will do several things for you.

1. Open the exhaust with larger diameter tubing
2. Get rid of the 500 crimps and smashed in sections of the OEM midpipe with smooth mandrel bends
3. Remove the OEM resonator box at the rear which turns out to also be a pretty large restriction.
4. Removes both secondary unmonitored cats which post zero risk of throwing a CEL light.
5. Save some weight to boot.

All of the same things apply to an N55 motor except for #4. The N55 is already a catless midpipe setup.

Originally Posted by 1speedbike

Hahahaha no $5 required, just keep making awesome stuff.

I'll make you yearly $1 payments on the bet where I just confirmed I lost.

[mke135i]

Does your system take care of the smell some people have reported when using catless downpipes?

[BerkTechnology]

Originally Posted by mke135i

Does your system take care of the smell some people have reported when using catless downpipes?

If your'e using the OEM downpipes or catted downpipes then the smell is non-existent.

The smell comes from running full catless.

[cstavaru]

Originally Posted by BerkTechnology

If your'e using the OEM downpipes or catted downpipes then the smell is non-existent.

The smell comes from running full catless.

Sorry, but this is far from the truth. Running with catless downpipes and stock midpipes the smell is already very strong.