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      05-31-2016, 07:44 AM   #1
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Down pipe questions

Sorry for the questions but new to the whole down pipe thing...

1) Will replacing the cats w/down pipes negatively affect the emissions testing?
2) Is the inspection shop looking the other way or do most shops not notice?
3) If the turbo adapts to the MPE and assuming other exhausts. Is this mod just for the sound?

Thanks.
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      05-31-2016, 10:08 AM   #2
ashburyn54
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Quote:
Originally Posted by masou
Sorry for the questions but new to the whole down pipe thing...

1) Will replacing the cats w/down pipes negatively affect the emissions testing?
2) Is the inspection shop looking the other way or do most shops not notice?
3) If the turbo adapts to the MPE and assuming other exhausts. Is this mod just for the sound?

Thanks.
A few answers. I have the VRSF catless DP installed. Any DP for the m235i will work. Make sure it's without a bracket.

Yes it will effect emissions and will trip a cel. There are various fixes. I would recommended jb4 or the i02 catsim. Avoid spacers of any sort.

Ask a head tech that's excited about the car and see what he says. It's likely he will just turn his cheek. They love that stuff just as much or more than we do.

Without a tune gains are minimal. Probably 10hp or so. Apparently with a tune you can see something close to 25whp or tq. If you have the MPE exhaust be prepared for it to be LOUD. Like straight pipe n55 loud on start up. Catless with the stock exhaust is much more aggressive than MPE or the Akra exhaust. Totally worth it though.
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      05-31-2016, 08:34 PM   #3
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Quote:
Originally Posted by ashburyn54 View Post

Yes it will effect emissions and will trip a cel. There are various fixes. I would recommended jb4 or the i02 catsim. Avoid spacers of any sort.
Well, the JB4 is not a fix. You can't pass inspection with it. You can use the JB4 to keep the CEL light off, but while the auto-clear is active, the car won't complete its readiness monitors, and therefore, will fail emissions. It only keeps the light off so it doesn't bother you, that's all.

The iO2 sim is the only current fix accepted across the board as working.

A spacer on an N55 is hit or miss, largely miss. But at least it has a chance of sneaking you through, vs. the JB4.
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Last edited by PrematureApex; 05-31-2016 at 08:50 PM..
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      05-31-2016, 08:43 PM   #4
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Quote:
Originally Posted by masou View Post
Sorry for the questions but new to the whole down pipe thing...

1) Will replacing the cats w/down pipes negatively affect the emissions testing?
2) Is the inspection shop looking the other way or do most shops not notice?
3) If the turbo adapts to the MPE and assuming other exhausts. Is this mod just for the sound?

Thanks.
I'll answer...

First off, you have one cat in the single DP (not multiple ).

Yes, going catless DP means you'll need a way to keep the o2 sensor CEL from tripping (and the readiness monitor completed).

This may be above your head at the moment but...

When you go for inspection in PA, you can't have any CELs. By way of background, a readiness test is completed for each of a plurality of emissions factors (evaporation, o2 sensor performance, EGR, etc.) prior to tripping the CEL (pass the test, no CEL, fail...CEL comes on). In PA you're allowed one not-ready monitor status. However, the o2 sensor monitor isn't normally the last test to clear with the N55 (the EVAP is). So the often-used method of resetting the ECU, driving around until all the readiness tests have passed sans the o2 sensor, then pulling into inspection before it completes, fails and trips the CEL, doesn't work. You need an o2 simulator (which tricks the ECU into thinking you're running a cat, thereby allowing the o2 readiness test to run, and pass)...there's only one out there now as mentioned above.

As posted above, maybe 10-15 whp peak with a tune, but gains in the 20-25 whp in the midrange...along with the sound "improvements". As someone who runs a DP on an N55, it's a noticeable performance increase in the mid-range. Whether or not it's worth it for you is a choice you'll have to make for yourself. Like many modern twin-scroll, DI cars...the exhausts are good enough from the factory that many choose to leave them alone.
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'14 N55 X1 (JB4, BMS DP, BMS Intake, Alpina TCU reflash, H&R Sports, Bilstein B6s, E93 M3 RSB, Strongflex FCABs, baby seat)
'08 N54 535xi touring (Bilstein B6s, Downpipes, MHD tune, baby seat)

Last edited by PrematureApex; 05-31-2016 at 08:49 PM..
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      06-01-2016, 09:17 PM   #5
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Quote:
Originally Posted by PrematureApex
Quote:
Originally Posted by ashburyn54 View Post

Yes it will effect emissions and will trip a cel. There are various fixes. I would recommended jb4 or the i02 catsim. Avoid spacers of any sort.
Well, the JB4 is not a fix. You can't pass inspection with it. You can use the JB4 to keep the CEL light off, but while the auto-clear is active, the car won't complete its readiness monitors, and therefore, will fail emissions. It only keeps the light off so it doesn't bother you, that's all.

The iO2 sim is the only current fix accepted across the board as working.

A spacer on an N55 is hit or miss, largely miss. But at least it has a chance of sneaking you through, vs. the JB4.
Agreed. That was my initial thought. Although I keep hearing people saying he has a 02 standalone "fix" or auto clear. Regardless It's not a test fix.
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      06-02-2016, 02:48 AM   #6
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Question for ashburyn54 can you smell fuel inside the cabin after the DP installation?
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      06-03-2016, 10:03 AM   #7
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Quote:
Originally Posted by Yellowflash21
Question for ashburyn54 can you smell fuel inside the cabin after the DP installation?
Not like fuel inside. Windows down and generous braking will bring a whiff past you. Smells great in my opinion
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