E90Post
 


TNT Racewerks
 
BMW 3-Series (E90 E92) Forum > E90 / E92 / E93 3-series Powertrain and Drivetrain Discussions > NA Engine (non-turbo) / Drivetrain / Exhaust Modifications > n52 exhaust cut out



Reply
 
Thread Tools Search this Thread
      07-24-2018, 04:12 PM   #1
gT-BMW
Lieutenant
United_States
203
Rep
437
Posts

Drives: 06' 325i 6spd
Join Date: Jan 2018
Location: FL

iTrader: (0)

Garage List
2006 BMW 325i  [0.00]
n52 exhaust cut out

Hey guys i already have AA headers so its primary cat delete and im thinking about deleting the secondary cats and add an exhaust cut out between the muffler and resonator. anybody running one of these? if so does it actually add power or decrease it? Does it sound like stock with it closed?
Appreciate 0
      07-25-2018, 09:40 AM   #2
atmosphericM
Basic Bimmer
United_States
518
Rep
935
Posts

Drives: E92 328i 6MT ///M
Join Date: Sep 2017
Location: B'ham

iTrader: (1)

Garage List
Do a search this was just discussed here a couple of months back.
__________________
Black Sapphire 328i ///M Sport Coupé
Save the Manuals!
Appreciate 0
      07-25-2018, 10:38 AM   #3
The Nightman
Cometh
The Nightman's Avatar
1067
Rep
1,287
Posts

Drives: Boy's Soul
Join Date: Jul 2016
Location: Boy's Hole

iTrader: (4)

Garage List
Seems pointless when you've already deleted all the cats. The rest of the exhaust isn't restrictive enough to warrant a cutout imo
Appreciate 1
Noir883.00
      07-25-2018, 10:47 AM   #4
Taskmaster
Banned
Japan
2463
Rep
9,004
Posts

Drives: M235i 6MT / E92 328 Msport 6MT
Join Date: Nov 2013
Location: Florida

iTrader: (6)

Quote:
Originally Posted by freedomfries View Post
Seems pointless when you've already deleted all the cats. The rest of the exhaust isn't restrictive enough to warrant a cutout imo
It is, but it will sound like shit, and could make less power depending* on where the cutout is.

Last edited by Taskmaster; 07-26-2018 at 09:38 AM..
Appreciate 2
Noir883.00
dwashy64.50
      07-26-2018, 09:59 AM   #5
nsjames
Brigadier General
2440
Rep
4,333
Posts

Drives: 08 328xi Touring
Join Date: May 2017
Location: ohio

iTrader: (0)

and 95% of the time they leak. so you'll always hear a terrible exhaust leak.

unless you buy realy quality units that are cost prohibitive.
Appreciate 0
      07-26-2018, 12:07 PM   #6
gT-BMW
Lieutenant
United_States
203
Rep
437
Posts

Drives: 06' 325i 6spd
Join Date: Jan 2018
Location: FL

iTrader: (0)

Garage List
2006 BMW 325i  [0.00]
Quote:
Originally Posted by atmosphericM View Post
Do a search this was just discussed here a couple of months back.
yes i was reading those threads, there were more towards the sound rather than performance. nobody was clear if it actually added hp.

Quote:
Originally Posted by freedomfries View Post
Seems pointless when you've already deleted all the cats. The rest of the exhaust isn't restrictive enough to warrant a cutout imo
so the stock muffler is not a restriction? if so thats sweet.

Quote:
Originally Posted by Taskmaster View Post
It is, but it will sound like shit, and could make less power depending* on where the cutout is.
I was always told the cutout mod on a bmw should be done towards the rear of the car or the afrs will be to crazy?

Quote:
Originally Posted by nsjames View Post
and 95% of the time they leak. so you'll always hear a terrible exhaust leak.

unless you buy realy quality units that are cost prohibitive.
I have a 2.5 dmh cutout from a previous n/a honda build that i did many years ago. still have it. and that one doesnt leak. Ive tried other cutouts, they did leak, they eventually leak because the housing butterfly slightly warps after awhile and the motors would break off or stop working. QTP was the worst. IMO dmh is the best cutout on the market.
Attached Images
   

Last edited by gT-BMW; 07-26-2018 at 12:14 PM..
Appreciate 0
      07-26-2018, 12:36 PM   #7
atmosphericM
Basic Bimmer
United_States
518
Rep
935
Posts

Drives: E92 328i 6MT ///M
Join Date: Sep 2017
Location: B'ham

iTrader: (1)

Garage List
Ok well here are my two cents:

1. It will sound like crap. Mufflers refine the tone. But if this is purely for when you are racing, then ok. To each his own I suppose, but there is a point when you are seriously infringing upon the comfort of those around you. When a modded Harley drives by and I literally have to plug my ears for them to not hurt, I roll my eyes so hard. I mean wtf, really. Some places even have laws against this, with good reason.

2. Yes it will probably give you about 5 whp to bypass the muffler. But you'll also hurt your hp a bit when it's closed because of the turbulence it will cause in the exhaust stream. Also, a tune is becoming more and more necessary to fully utilize your exhaust mods with each one you do. Personally I wouldn't even run headers without an aftermarket tune as they're already probably affecting the AFR's (not sure how much our DME's can "adjust" to engine air mods). With catless headers, catless front pipes, and an open cutout, the air flow is so much freer and different than stock, a tune is really needed to enjoy the benefits. Without a tune, some top-end HP gains may be happening, but almost certainly at the expense of low-end TQ.

3. I could be wrong but I'm thinking that there is only one place you can even put the cut-out, which will require a different mid-pipe (y-pipe), because in stock form, the resonator is in this location. The rest of the exhaust "area" under the car is pretty tight... but perhaps you could find another location... maybe.

4. Would it sound like stock with it closed? No. You already have headers, your car already doesn't sound like stock. If you delete the secondary cats, your car is going to get louder and raspier. It wont be super loud or raspy, thanks to your stock muffler, but it will be noticeably different than stock when the motor is under load. With a cut-out it will be deafening and, to anyone above the age of 25, annoying AF.

5. There is at least one good YouTube video of a guy with a cutout on his 328i. That should give you an idea of sound.
__________________
Black Sapphire 328i ///M Sport Coupé
Save the Manuals!

Last edited by atmosphericM; 07-26-2018 at 12:43 PM..
Appreciate 1
gT-BMW203.00
Reply

Bookmarks

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off



All times are GMT -5. The time now is 07:17 AM.




e90post
Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
1Addicts.com, BIMMERPOST.com, E90Post.com, F30Post.com, M3Post.com, ZPost.com, 5Post.com, 6Post.com, 7Post.com, XBimmers.com logo and trademark are properties of BIMMERPOST