diy downpipe - OEM retrofit - No cel

paul_sarky · 08-15-2016, 05:42 PM

An idea came to my mind. About 15 years ago i took a catalytic converter off an old car and punched a hole thru, put it back on and instant power, that little v6 came to life. Of course, the check engine light came on and eventually i replaced it with a new unit.

So, cant we do the same with our downpipes? But, instead of just making a hole, put a long ceramic or some high heat steel pipe thru it long enough to go past the second 02 sensor. This way, the catalytic converters would still be doing their job, but depending on the diameter of the pipe, you would have some of the gasses free flowing, releasing the exhaust pressure and not trigger the check engine light.

what do you guys think?

MattPro · 08-16-2016, 08:50 PM

If this could provide a gain, there's definitely no room for it. With how big those cats are right behind our engine there's no room to fit a parallel pipe of substantial size. Nothing that could provide a gain at least. Also, with the angle our cats are at, the exhaust would have to change directions twice. This could honestly slow it down more than a catalytic converter could.

If you want an OEM fix, you could pick up a set of M5 downpipes. Less restrictive and factory fit.

08-15-2016, 05:42 PM	#1
paul_sarky Private 38 Rep 99 Posts Drives: 2012 BMW 550i M-Sport Join Date: Sep 2015 Location: Seattle, WA iTrader: (0)	diy downpipe - OEM retrofit - No cel - idea An idea came to my mind. About 15 years ago i took a catalytic converter off an old car and punched a hole thru, put it back on and instant power, that little v6 came to life. Of course, the check engine light came on and eventually i replaced it with a new unit. So, cant we do the same with our downpipes? But, instead of just making a hole, put a long ceramic or some high heat steel pipe thru it long enough to go past the second 02 sensor. This way, the catalytic converters would still be doing their job, but depending on the diameter of the pipe, you would have some of the gasses free flowing, releasing the exhaust pressure and not trigger the check engine light. what do you guys think?
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08-16-2016, 08:50 PM	#2
MattPro Private First Class 65 Rep 163 Posts Drives: '13 F10 550iX, '91 E30 Join Date: Dec 2015 Location: Chicago Burbs iTrader: (0)	If this could provide a gain, there's definitely no room for it. With how big those cats are right behind our engine there's no room to fit a parallel pipe of substantial size. Nothing that could provide a gain at least. Also, with the angle our cats are at, the exhaust would have to change directions twice. This could honestly slow it down more than a catalytic converter could. If you want an OEM fix, you could pick up a set of M5 downpipes. Less restrictive and factory fit. __________________ Thanks, Matt 2013 F10 550iX Carbon Black/MSport BMW Fault Code DB
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