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BMW 523i E39 header advice.

14K views 24 replies 3 participants last post by  nzm 
#1 ·
#2 ·
E-bay headers are an interesting trend. I actually just purchased a set myself and they are very legit. I was able to compare them side by side to a set of Supersprint headers and they looked almost identical. I was also able to determine the manufacturer so if I ever have a problem I know who to call. I haven't installed them yet, but in order to do so and pass emissions I need a high flow cat (something like yours) and to reposition the O2 sensors.

IMO anything is better than the headers that come stock. The ones in the E39 look like two pieces of metal crimped together. I think they're worth a shot.
 
#3 ·
Hi, thanks for posting. Can you give me a link to your headers or a manufacturer. The price is real good (the ones in my post) and they look great. Here in my country a set of nonames costs about 400$. On ebay the actual shippment cost more but i can still get them for less than 200 :)
 
#6 ·
Yeah, there really should not be much of a difference between any of these e-bay headers. More than likely the same manufacturer makes them and I know they are modeled off of something else much more expensive.

When I purchased mine I just wanted to make sure the welds on them looked good, and the bends were smooth. I ended up being pretty surprised by the quality. I'm probably going to ceramic coat them and then have my shop fabricate whatever I need to pass emissions.
 
#7 ·
Well when i bought the car it had no oxygen sensors, they were canceled because i have no erors on OBC. After changing the exhaust and the cat. my emissions were 3 or 4 times bigger, i had to bribe the guy :D Hope it works next year too :D
 
#9 ·
How did you find the changes in performance before and after your exhausts, cat and headers individually? Which part made the biggest inmprovement and what was the best improvemet? Fuel economy, 0-100kms sprint, top end power?

I am interested as I will eventually be doing the same to mine and this info will come in handy I doubt I'll be doing it all at once, prob bit by bit from muffler to header.

Cheers!
 
#11 ·
So u reckon high flow cat back exhaust system with better flowing mufflers at the rear and upgrading to the M50 kit? Wat exhaust system would you recommend and if I were to get a custom in welded with magnaflow
mufflers an high flow cat, would 3"
all the way be sufficient or is that too large? I got a mate who does alot of TIG and MIG welding he could probably make me a custom
exhaust unless there are good ones available easy to purchase somewhere in Melbourne Australia? Am new to euros jap cars I know inside out but euros I don't know hardly anything lol
 
#12 ·
The 2,5 and 2,8 engines are limited through the 2 original cats., muffer and intake. By removing the cat. and fitting in a high flow muffer you can get the real power of an 2.5 m50 for example. I don't have all the exhaust changer, i modified the resonator and made it dual exhaust like the M5. It is recomended not to remove the resonator because you will lose torque.
 
#13 ·
Yeh I can feel that the motor is definitely being held back. I reckon after modifying the breathing it will be possible to unlock up to 50hp? Or am I dreaming?

Thanks for the advice Duxter, will change the exhaust and post before and after dyno results as we have one in the shop here.
Btw - wat is 200cp+? it's another measurent of power I'm assuming, but haven't seen it before.

Cheers
 
#17 ·
Ahh ok lol thank you!

I read in the manual that our cars have 172hp from factory or something like that...so if you are getting 200cp+ at the wheels with a STD ECU that proves how restricted the engine is from factory. What does 200cp feel like to drive in the 523? Is it noticeable from acceleration, mid range or top end?

Sorry for all the question haven't had my car long and am about to start modifying it.

Thanks!
 
#18 ·
The m50 intake helps a lot from 5500 to 6500 because with the stock manifold the car just can't accelerate from 5500. A little downside si the fact that you loose about 10nm of torque and it feels a little but jus a little until 2500-3000, but from 3000 it's just another car, it feels great for a 2.5 and 1500kg car. A chip tuning helps with the torque and about 18-20bhp which it is noticeable in low range RPMs.
 
#19 ·
Sounds like the M50 I take conversion kit is definitely the way to go then. So you have to replace the entire manifold? I saw a kit which looked like black plastic
- surely that can be right?

What air filter are you running? Or have unupgraded to a CAI with pos filter? The standard airbox looks like it can be kept
with only the filter element needing
to be upgraded. So you know if K&N make a flat panel
filter element for our cars?
 
#20 ·
:d

Some Pics:


Be careful with the hose, you need a realy strong one because of the vacuum, i've changed it 2 times now, this one is 45bar's :D The one in the picture was sucked up because of the vacuum.
 

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#23 ·
Wow that's incredibly cheap. On the net I can't find it for less than $300 for a ful kit with hoses and everything, including the 'critical vacuum hose' they call it or something lol.

Way do you mean by u roved the resonator? Isn't resonator part of the exhaust system between the cat and mufflers? Over here it is...
 
#25 ·
Ahh ok cheers for that. I'm still suprised at how much detail there are in these BMW engines - every individual system in the car has so much to it. Previous to this I modified and owned japanese cars. They were much, much simpler mechanically and I could
take apart the entire car in my garage and put it back together. The headlight
system alone in this car seems more sophisticated than the whole
car was lol
 
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