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. |
05-31-2016, 10:08 AM | #2 | |
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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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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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'02 S54 M3 (500/500 GC/Koni)
'08 N54 135 (JB4, DCI, BMW PS/Bilstein B6s, H&R M3 FSB, Strongflex FCABs) '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 08:50 PM.. |
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05-31-2016, 08:43 PM | #4 | |
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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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'02 S54 M3 (500/500 GC/Koni)
'08 N54 135 (JB4, DCI, BMW PS/Bilstein B6s, H&R M3 FSB, Strongflex FCABs) '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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06-03-2016, 10:03 AM | #7 | |
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