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      06-29-2010, 10:30 AM   #17
crfine88
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Drives: E86M
Join Date: Jan 2009
Location: Cave Creek AZ.

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OEM Euro Headers

#16

I was finally content with my suspension and tires, so I decided to look into power and braking modifications. After spending countless hours immersed in this and other Z4 forums, I realized that there was not a quick and easy way to significantly increase the power / driving performance in our cars.
The goal was to get more HP and torque in the low end, and get rid of the speed governor. In the category of performance upgrades these are some that were up for consideration:

1. ESS tune: The general consensus on the forms was that this tune greatly improved and amplified the cars driving characteristics. Quicker acceleration response, more consistent power band, no governor.

2. Headers: This seemed to be the mod that would generate the greatest gains, especially when paired with a tune. Our US headers have Primary cats right of the engine which restrict airflow immediately. The euro and all aftermarket headers do not have cats in line with the headers, so the restriction is gone.


3. Intake: It seemed that while they all sound awesome, the dyno result were not showing any significant gains. In some cases the aftermarket intake would cause a loss in HP.

4. Gears: Rave reviews from everyone who has changed their gearing. Better throttle response, minimal affect on gas mileage. Only cautionary tip was to buy a rear diff with the gears installed by someone who will offer a warranty ( because, “they can grenade”).

5. F/I: The most significant gains, and the most expensive. Also was not sure how I felt about forced induction at the time.

After considering all of the mods above, I decided to go with the tune / header combo. For the headers, I decided to go with OEM euro headers. I was going to pick these up from Tischer BMW http://www.trademotion.com/partlocat...catalogid=4462. Tischer had the best price on new headers at the time. Before I pulled the trigger with Tischer, I got lucky; a member in CA was selling a used set. I am always looking for an excuse to take a road trip in the M, so my wife and I headed out to CA to pick up the headers.


Installation: The installation was time consuming. I removed the entire exhaust system to get to the headers. The headers married up perfectly, but it was a little tricky getting the second header in after installing the first. If I were to do this again, I would try to put both headers into position at the same time. Installed the Primary O2 sensors and removed the secondaries since they now had nowhere to go. At the time, I knew I would have to relocate the sensors. I learned from ESS that while they can get rid of the secondary O2’s with a tune, this was not a good idea. Our computers use data from the secondary’s to optimize performance.


Initial impressions: Good Mod! More power under foot! This really helped the low end and initial acceleration. There was significant change in sound as well. A louder more throaty sound was being produced. As expected, engine codes. Two codes, one for each missing secondary 02 sensor.


PROS:
1. Minimum 15 whp gain and 10 lbs torque gain without a tune, and promise for close to 30 whp gain with a proper tune.
2. OEM parts, with OEM fitment.
3. 8lbs lighter than US headers.
4. Very involved install, good bonding experience with the M.
5. Under foot response is greatly improved.
6. Sounds good.

CONS:
1. Committed to dealing with the secondary O2’s once you do this mod.
2. Some of the hardware is difficult to get to while installing the headers.
3. Had to perform a small miracle to get both headers in (I believe this could be avoided by putting both into position at the same time).

If I were to do this again:
1. I would have modified the mid pipe and lengthened the secondary O2’s first.
2. I would have ceramic coated the headers.
3. I would have tried to put both headers into position before installing the hardware.


Overall I was very happy with this mod, and believe this is the best “bang for the buck” when it comes to power modifications. The pictures below give an idea of the installation process.
Attached Images
                   
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Last edited by crfine88; 07-07-2010 at 09:14 AM..
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