E90 w/ catless DPs how to finish exhaust?

madbim · 05-16-2019, 12:31 PM

I recently drove an 2019 x3 40i which sounded excellent!

I have an E90 with catless downpipes, I'm torn on how to get a little more sound out of it without being obnious or adding drone.

Should I replace the secondary cats with vibrant resonators and keep the OEM resonator?

Should I keep the OEM secondary cats and replace the resonator with an X pipe?

Should I do both? Muffler delete is not an option.

type-dRew · 05-16-2019, 02:02 PM

I would always do the things that netted me a power gain over purely sound first. So first I would delete the secondary cats or gut them, whichever. That will get you a decent bit of sound a few whp.

If you still wanted more sound than that id say delete the reso with a h/x pipe.

05-16-2019, 02:40 PM

Quote:

Originally Posted by type-dRew

I would always do the things that netted me a power gain over purely sound first. So first I would delete the secondary cats or gut them, whichever. That will get you a decent bit of sound a few whp.

If you still wanted more sound than that id say delete the reso with a h/x pipe.

Well, in the case of the E90 the resonator is what restricts most of the sound OP is looking for; that's obviously the best place to start.

IMO removing the secondary cats and ending up with a stinky/nasty smelling car isn't worth what little there is to be gained...replacing them with high flow cats would also be an option.

cgbimmer · 05-16-2019, 03:50 PM

So I went thru alot steps ..on my buddy's car [[[ if I find pics will up load ..
I have 07 335xi
vrsf downpipe first I took of resonator welded x-pipe at same time took of second cats..
also opened rear muf and saw drivers side resonator cut out put solid pipe in tight fit and passenger side had perforated pipe so I cut a pipe same size in half and welded it over holes instead of cutting out ..took out half of insulation sound stuff in there
I thought sounded good but loud I got pulled over and got warning in ct crazy..
did not like smell either so dropped again and put back just rear cats and still sounds good but no drone and can not smell with windows down..
I know that is long but wanted to point out what I went thru ..

madbim · 05-16-2019, 04:35 PM

Should have added I don't want rasp if possible.

Sounds like deleting the resonator is a good place to start?

madbim · 05-19-2019, 10:59 AM

I purchased a 2.5" xpipe, will update once installed.

bjf66 · 05-20-2019, 07:07 AM

Quote:

Originally Posted by madbim

I purchased a 2.5" xpipe, will update once installed.

Which one did you get? I'm also considering your path.

Stock 335is muffler, would probably do X-pipe first, then hi-flow downpipes, then maybe resonators.

Hope you can make videos before and after if you do it!

05-16-2019, 12:31 PM	#1
madbim Private First Class 32 Rep 160 Posts Drives: 08' E90 335xi Join Date: May 2011 Location: Madison, WI iTrader: (0)	E90 w/ catless DPs how to finish exhaust? I recently drove an 2019 x3 40i which sounded excellent! I have an E90 with catless downpipes, I'm torn on how to get a little more sound out of it without being obnious or adding drone. Should I replace the secondary cats with vibrant resonators and keep the OEM resonator? Should I keep the OEM secondary cats and replace the resonator with an X pipe? Should I do both? Muffler delete is not an option.
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05-16-2019, 02:02 PM	#2
type-dRew Major 641 Rep 1,245 Posts Drives: 2009 335i xDrive Join Date: Feb 2019 Location: Newport MI iTrader: (0)	I would always do the things that netted me a power gain over purely sound first. So first I would delete the secondary cats or gut them, whichever. That will get you a decent bit of sound a few whp. If you still wanted more sound than that id say delete the reso with a h/x pipe. __________________ 2009 335i xDrive AT / 177k+ miles PSP 750ic / Fuel-It! Stage 1 / BMS CP / Sutphin Tuning / RFP E50 11.61 @ 117.5 New setup; Covid 19Ts on RFP 93 + ARM inlets, dp, VTT cp and PSP outlets
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05-16-2019, 03:50 PM	#4
cgbimmer 2007 335xi 31 Rep 69 Posts Drives: 2007 335xi blue Join Date: Mar 2015 Location: bloomfield ct iTrader: (0)	So I went thru alot steps ..on my buddy's car [[[ if I find pics will up load .. I have 07 335xi vrsf downpipe first I took of resonator welded x-pipe at same time took of second cats.. also opened rear muf and saw drivers side resonator cut out put solid pipe in tight fit and passenger side had perforated pipe so I cut a pipe same size in half and welded it over holes instead of cutting out ..took out half of insulation sound stuff in there I thought sounded good but loud I got pulled over and got warning in ct crazy.. did not like smell either so dropped again and put back just rear cats and still sounds good but no drone and can not smell with windows down.. I know that is long but wanted to point out what I went thru .. __________________ 2007 335xi Daw stage 2 old wheel custom 2.25 relocation inlets vrsf alum outlets.Vrsf 5'' stepped intercooler.stage 2 bucket lpfp.BQ tune xhp stage 3 tranny flash.vrsf downpipes modified 3in exhaust.ER charge pipe tial bov.Custom oil cooler..cic retrofit.koni shocks h@r sport spring staggered conti tir
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05-16-2019, 04:35 PM	#5
madbim Private First Class 32 Rep 160 Posts Drives: 08' E90 335xi Join Date: May 2011 Location: Madison, WI iTrader: (0)	Should have added I don't want rasp if possible. Sounds like deleting the resonator is a good place to start?
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05-19-2019, 10:59 AM	#6
madbim Private First Class 32 Rep 160 Posts Drives: 08' E90 335xi Join Date: May 2011 Location: Madison, WI iTrader: (0)	I purchased a 2.5" xpipe, will update once installed.
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