exhaust modification questions

rothwem · 11-30-2009, 09:21 AM

I looked under the car the other day, and I noticed that my exhaust goes from two pipes to one at the resonator.

Has anyone tried putting a 2 in, 2 out resonator in place of the stock resonator, then using a 2 in, 2 out muffler in place of the stock muffler?

Also, will the car pass emissions without the secondary cats? Are there any O2 sensors behind them? Has anyone found a set of race cats that will work?

BigZ88 · 11-30-2009, 12:20 PM

as far as benefits are concerned I'd hesitate to say this would gain you anything.

I'm not sure about secondary O2's but if not the only way they will not pass is if you have sniff testing in your state. If they purely check for codes then you'd be fine.

11-30-2009, 09:21 AM	#1
rothwem Major 497 Rep 1,208 Posts Drives: 2009 BMW 328i Wagon Join Date: Apr 2009 Location: Asheville, NC iTrader: (0) Garage List 2009 BMW 328i [10.00]	exhaust modification questions I looked under the car the other day, and I noticed that my exhaust goes from two pipes to one at the resonator. Has anyone tried putting a 2 in, 2 out resonator in place of the stock resonator, then using a 2 in, 2 out muffler in place of the stock muffler? Also, will the car pass emissions without the secondary cats? Are there any O2 sensors behind them? Has anyone found a set of race cats that will work?
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11-30-2009, 12:20 PM	#2
BigZ88 Cap'n Winky 23 Rep 174 Posts Drives: e90 330i Join Date: Oct 2009 Location: Greer, SC iTrader: (0)	as far as benefits are concerned I'd hesitate to say this would gain you anything. I'm not sure about secondary O2's but if not the only way they will not pass is if you have sniff testing in your state. If they purely check for codes then you'd be fine.
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