Custom exhaust on my N52 question

Polo609 · 03-16-2013, 01:12 PM

I'm doing a 325i to a 335i exhaust conversion but want to go bigger than stock for the piping.

What do you guys suggest? I have no mods in the engine, but do plan on doing the IM swap from a 330i plus tune.

SDemetris · 03-16-2013, 02:17 PM

I would keep stock diameter if you are getting rid of the resonator and getting better flowing mufflers. otherwise you will be really loud and might actually lose power.. mapleridge got bigger diameter pipes a while ago and he dynoed for a loss of power. so i would just get rid of some of the restrictions but keep stock diameter

6MT_Addict · 03-16-2013, 07:21 PM

+1

Give this a read for basic info on exhaust upgrades, pipe diameter is that size for a reason: http://www.torquecars.com/tuning/sports-exhausts.php

"To try to deter our younger readers from sticking the largest exhaust they can find we add the following general tip. As a very very general rule of thumb, under a 1.6l engine, TorqueCars recommend you stick with a maximum 1.5 to 2 inch pipe (the smaller the engine the smaller the bore size). Under 2.5l engines go with 2-2.5 inches and over this go with a 3 inch exhaust.

Over 2.5 litre engines we would suggest a twin exhaust system using half the engine size to determine the optimum pipe size as we have just outlined. so a 3.0 Engine would be ideally suited to a twin 1.5-2 inch bore and 5 litres with a 2-2.5 inch twin bore." - taken from the link above

Polo609 · 03-18-2013, 03:26 PM

Read the article and sounds good, but whats the stock piping diameter from the N52?

just4kickz · 03-18-2013, 03:54 PM

if you want at true dual you might need to do some modifications to that area right under the trunk... or else the piping is going to be uneven...

Route 16 · 03-18-2013, 04:06 PM

Pipe is 2.5 inches all the way, I have 3in from header flange to muffler, I lost back pressure, maybe a little louder, but it's like how you would blow through a straw rather than those small coffee straws.

MikeR1994 · 03-21-2013, 07:42 AM

Quote:

Originally Posted by Route 16

Pipe is 2.5 inches all the way, I have 3in from header flange to muffler, I lost back pressure, maybe a little louder, but it's like how you would blow through a straw rather than those small coffee straws.

It's actually 2.25" just after the header and it comes down to 2" within a couple inches.

OneWhiteF30 · 03-28-2013, 10:05 AM

Quote:

Originally Posted by Route 16

Pipe is 2.5 inches all the way, I have 3in from header flange to muffler, I lost back pressure, maybe a little louder, but it's like how you would blow through a straw rather than those small coffee straws.

Did the car throw any codes when you did 3" header back?

Route 16 · 03-28-2013, 10:30 AM

Quote:

Originally Posted by DirtyE90

Did the car throw any codes when you did 3" header back?

No that only happens when you play with your headers, those have the O2 sensors. The pipes after the headers are just metal, nothing else.

Rival · 04-01-2013, 08:29 AM

i would delete the 2nd cats. delete the stk res and put in two virbrant res's in the 2nd cat places, than may add a bullet race muffler in place of the rear muffler.

the vibrant resonator's act alot like mufflers from what i hear.

chaFT328i · 04-01-2013, 08:24 PM

Anyone ever considering deleting res and replacing stock 2nd Cats for high flow cats? Seems pretty reasonable for those who want a nice pur(NOT roar) and some gains for smaller cost.

03-16-2013, 01:12 PM	#1
Polo609 Private 5 Rep 78 Posts Drives: 06 325i sport package Join Date: Aug 2010 Location: Tdot iTrader: (0)	Custom exhaust on my N52 question I'm doing a 325i to a 335i exhaust conversion but want to go bigger than stock for the piping. What do you guys suggest? I have no mods in the engine, but do plan on doing the IM swap from a 330i plus tune.
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03-16-2013, 02:17 PM	#2
SDemetris FSAE Dude 61 Rep 759 Posts Drives: E90 328xi Join Date: Jul 2012 Location: Pittsburgh, PA iTrader: (0)	I would keep stock diameter if you are getting rid of the resonator and getting better flowing mufflers. otherwise you will be really loud and might actually lose power.. mapleridge got bigger diameter pipes a while ago and he dynoed for a loss of power. so i would just get rid of some of the restrictions but keep stock diameter __________________ 2007 TiAg 328xi: AA Tune, AFE intake, Full exhaust, 335xi Brakes, H&R RSB, UUC FSB, H&R Sports, Billy Sports...BBS SR 17x8 1985 Gazelle Beige 325e: Poly everything, e24 3.25 LSD, 225 lb weight reduction, Corbeau FX1, Shifter machined by me, roll bar, harness, all the other goodies. My "Racecar"...15x7 BBS RA
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03-16-2013, 07:21 PM	#3
6MT_Addict Captain 283 Rep 888 Posts Drives: 08 135i M Sport 6MT, 15 X3 35i Join Date: Feb 2013 Location: Edmonton iTrader: (2) Garage List 2008 BMW 135i [10.00]	+1 Give this a read for basic info on exhaust upgrades, pipe diameter is that size for a reason: http://www.torquecars.com/tuning/sports-exhausts.php "To try to deter our younger readers from sticking the largest exhaust they can find we add the following general tip. As a very very general rule of thumb, under a 1.6l engine, TorqueCars recommend you stick with a maximum 1.5 to 2 inch pipe (the smaller the engine the smaller the bore size). Under 2.5l engines go with 2-2.5 inches and over this go with a 3 inch exhaust. Over 2.5 litre engines we would suggest a twin exhaust system using half the engine size to determine the optimum pipe size as we have just outlined. so a 3.0 Engine would be ideally suited to a twin 1.5-2 inch bore and 5 litres with a 2-2.5 inch twin bore." - taken from the link above __________________ 2015 Cosmic Blue Metallic Wrapped X3 35i ///M Sport Full 3M Vinyl Wrap \| Flat Black Grilles
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03-18-2013, 03:26 PM	#4
Polo609 Private 5 Rep 78 Posts Drives: 06 325i sport package Join Date: Aug 2010 Location: Tdot iTrader: (0)	Read the article and sounds good, but whats the stock piping diameter from the N52?
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03-18-2013, 03:54 PM	#5
just4kickz boku no namae ha... 336 Rep 11,025 Posts Drives: 2006 BS 330i Join Date: Feb 2006 Location: S. Bay Area, CA + Newark, NJ + ChiCity + True Blue iTrader: (11) Garage List 2006 E90 330i [0.00]	if you want at true dual you might need to do some modifications to that area right under the trunk... or else the piping is going to be uneven... __________________ looking for a PreLCI Black Sapphire e90 front bumper without license plate holes "Akimbo shotguns. Broken wrists anyone? And don't give me that 'it's just a game' bull**. Where the are my akimbo interventions then?! One scope on each eye mother**er!!"
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03-18-2013, 04:06 PM	#6
Route 16 I got lei'd 844 Rep 7,593 Posts Drives: '10 E90 M3 Join Date: Sep 2011 Location: Dark Side of the Moon iTrader: (62)	Pipe is 2.5 inches all the way, I have 3in from header flange to muffler, I lost back pressure, maybe a little louder, but it's like how you would blow through a straw rather than those small coffee straws.
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04-01-2013, 08:29 AM	#10
Rival Captain 66 Rep 790 Posts Drives: 95 z28 Join Date: Jul 2012 Location: shytown iTrader: (0)	i would delete the 2nd cats. delete the stk res and put in two virbrant res's in the 2nd cat places, than may add a bullet race muffler in place of the rear muffler. the vibrant resonator's act alot like mufflers from what i hear. __________________ 2010 335i M sport 2008 328i 2006 325i 1995 Z28 6spd - 377rwhp rip
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04-01-2013, 08:24 PM	#11
chaFT328i Second Lieutenant 9 Rep 208 Posts Drives: e90 07 328i Join Date: Sep 2011 Location: SoCal 626 iTrader: (2)	Anyone ever considering deleting res and replacing stock 2nd Cats for high flow cats? Seems pretty reasonable for those who want a nice pur(NOT roar) and some gains for smaller cost.
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