Removing Secondary Cats

Fraggy · 02-14-2008, 12:26 PM

If I were to remove the secondary cats, what effect on sound should I expect to get? Will it be louder? Will there be drone? Will the sound have a "sharper' edge? Sorry to sound like an idiot, but Ive never removed those parts before.

jjhan85 · 02-14-2008, 01:04 PM

yes it will sound louder...but i dunno if its a good thing... =\

not too sure

Gen_E92 · 02-14-2008, 01:24 PM

i recall ur current set up already has some drone, so I wouldn't recommend doing that.

Fraggy · 02-14-2008, 01:32 PM

Hmmm, I see. Whats happened is that over the last 500 miles or so, the exhaust is getting quieter

Sometimes I cant even hear it anymore except under hard acceleration. The drone is still there, maybe not as pronounced as before, but the nice sounds are getting quieter as well.

arabbmw · 02-14-2008, 05:10 PM

what kind of piping do you have now?

I was told by a guy who is really good with exhausts that removing the secondary cats and putting in x pipes is the way to go. Also seen it backed up here on the forums.

Fraggy · 02-14-2008, 05:13 PM

Piping is stock now...

cn555ic · 02-14-2008, 08:17 PM

Thats the first I have heard a exhaust getting quieter as it gets broken in!! Maybe you are just getting used to it...I also feel that my CP-E exhaust is getting quieter also...I think its me being adapted and used to the noise now after 2 weeks since the install...

Panoz · 02-19-2008, 01:31 AM

The change of sound is not really that big. There is a "metalic" baritone sound at 2000-3000 (as westwest888 mentioned).

There are some annoying sounds at cold start ,but when you reach the appropriate temperatures its fine.

In general , i would propose you not to delete the secondary ones but replacing them with HFC instead (100s maybe?).

Fraggy · 02-19-2008, 09:52 AM

Thanks guys, I will leave them in. Ive already replaced the Corsa with the fake Eisenmann for now.

02-14-2008, 12:26 PM	#1
Fraggy Brigadier General 193 Rep 3,469 Posts Drives: 2016 M3 Join Date: Jun 2005 Location: San Diego iTrader: (11)	Removing Secondary Cats If I were to remove the secondary cats, what effect on sound should I expect to get? Will it be louder? Will there be drone? Will the sound have a "sharper' edge? Sorry to sound like an idiot, but Ive never removed those parts before. __________________ 2016 Alpine White M3 (gone) 2019 Alfa Romeo Guilia (Totaled) 2020 Car-less 😁 (no more) 2020 M340
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02-14-2008, 01:04 PM	#2
jjhan85 J-Han 5 Rep 398 Posts Drives: BMW E90 325i jetblack Join Date: Mar 2006 Location: Maryland iTrader: (0) Garage List 2006 325i Sport Pac ... [0.00]	yes it will sound louder...but i dunno if its a good thing... =\ not too sure __________________ 325i // Sport Package // 6 speed manual // AFE intake // Resonator + Muffler Delete // 20% tints//
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02-14-2008, 01:24 PM	#3
Gen_E92 Brigadier General 118 Rep 3,432 Posts Drives: slow Join Date: Oct 2006 Location: Vancouver iTrader: (17) Garage List 2007 335i [7.80]	i recall ur current set up already has some drone, so I wouldn't recommend doing that.
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02-14-2008, 01:32 PM	#4
Fraggy Brigadier General 193 Rep 3,469 Posts Drives: 2016 M3 Join Date: Jun 2005 Location: San Diego iTrader: (11)	Hmmm, I see. Whats happened is that over the last 500 miles or so, the exhaust is getting quieter Sometimes I cant even hear it anymore except under hard acceleration. The drone is still there, maybe not as pronounced as before, but the nice sounds are getting quieter as well. __________________ 2016 Alpine White M3 (gone) 2019 Alfa Romeo Guilia (Totaled) 2020 Car-less 😁 (no more) 2020 M340
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02-14-2008, 05:10 PM	#5
arabbmw Lieutenant 16 Rep 548 Posts Drives: 335i coupe Join Date: Nov 2007 Location: G hills iTrader: (2)	what kind of piping do you have now? I was told by a guy who is really good with exhausts that removing the secondary cats and putting in x pipes is the way to go. Also seen it backed up here on the forums.
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02-14-2008, 05:13 PM	#6
Fraggy Brigadier General 193 Rep 3,469 Posts Drives: 2016 M3 Join Date: Jun 2005 Location: San Diego iTrader: (11)	Piping is stock now... __________________ 2016 Alpine White M3 (gone) 2019 Alfa Romeo Guilia (Totaled) 2020 Car-less 😁 (no more) 2020 M340
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02-14-2008, 08:17 PM	#7
cn555ic 441 Rep 18,331 Posts Drives: 335i Join Date: Jun 2007 Location: US iTrader: (6)	Thats the first I have heard a exhaust getting quieter as it gets broken in!! Maybe you are just getting used to it...I also feel that my CP-E exhaust is getting quieter also...I think its me being adapted and used to the noise now after 2 weeks since the install...
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02-19-2008, 01:31 AM	#8
Panoz Lieutenant Colonel 82 Rep 1,575 Posts Drives: E92 Space Grey 335i ,Aero Kit Join Date: Nov 2006 Location: EU iTrader: (0)	The change of sound is not really that big. There is a "metalic" baritone sound at 2000-3000 (as westwest888 mentioned). There are some annoying sounds at cold start ,but when you reach the appropriate temperatures its fine. In general , i would propose you not to delete the secondary ones but replacing them with HFC instead (100s maybe?). __________________ Procede V4 , Catless DPs, Forge FMIC, Injen Intake, VK Oilcooler, Hartge Quads Exhaust, Modded CDV, Synapse BOV Kit, BMW Performance 335i SSK Kit, P3 vent boost gauge Space Grey 335i -> See more pics HERE
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02-19-2008, 09:52 AM	#9
Fraggy Brigadier General 193 Rep 3,469 Posts Drives: 2016 M3 Join Date: Jun 2005 Location: San Diego iTrader: (11)	Thanks guys, I will leave them in. Ive already replaced the Corsa with the fake Eisenmann for now. __________________ 2016 Alpine White M3 (gone) 2019 Alfa Romeo Guilia (Totaled) 2020 Car-less 😁 (no more) 2020 M340
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