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This install guide is for the Flat 6 Motorsport diverter valves, but can also be used as a guide for the front bumper removal on a 95b Porsche Macan.


I always like to start from the top and make my way down. It is useful to have a lift for this project but is not necessary.

Tools needed are:
Small Flat Head Screwdriver
A T25 Torx
A T27 Torx
Socket Wrench for Torx sockets
Pliers of some sort to remove the spring clamps


First Step is to open the hood of the vehicle and take a look at what all will need to be removed. Start by removing the 4 clips that are at each corner of the plastic shield (red arrows in the picture.) To remove these clips simply insert a flat head screwdriver into the the side of the clip and pry up the middle section.


Next Step is the remove the hood latch handle. To do this you need to remove a slide clip that is holding the handle in place then wiggle the handle back and forth as you pull up. Not much force needs to be applied but it might be a little tight.


Here is a picture of all the clips that need to be removed.


Now you need to remove the screws holding the top of the bumper. There are 2 T25 torx screws and 2 T27 torx screws. The T25 screws are the ones on the outside and the T27 screws are the 2 on the inside. The T27 screws are reverse thread and will not fully remove from the bumper. Notate how far the T27 screws are screwed in for reinstall.


On the side of the vehicle under the headlight there is a plastic panel. There are 2 clips holding this on. Remove the 2 clips the same way you did on the top panel. Once the clips are removed you can remove the plastic panel. The panel is snapped in on the underside so just pull up. Do the same on the other side.


Now you have access to 2 more T25 screws. Remove these. Do the same on the other side.


Start the vehicle and turn the wheel to the opposite side you are working on. This will gain you access to the 4 T25 screws that hold on the fender liner. Remove the 4 screws that hold in fender liner. Use your fingers or a small screwdriver to pry the fender liner out from the bumper. Do the same on the other side.


Once the fender liner is pulled back you will see a black bracket. There are 2 T25 screws that are tucked into 2 pockets. Remove the 2 screws. Do the same on the other side.



Move down to the underside of the vehicle and remove the T25 screws and 2 clips holding the under panel on. You do not have to remove the panel completely if you don't want to but it is easier. There are 7 bumper tabs that are held on by T25 screws, 5 are visible and 2 are under the side underpanel.




On the passenger side there are 2 connectors that are located in the fender well. Unplug both connectors, They can be really tight from all of the dust/rocks/dirt that gets stuck in the connector.

Everything is now removed to remove the bumper. Slide the bumper forwards and it will come off. This is much easier with a helping hand.

Now that the bumper is removed you have access to the diverter valves. They are located towards the bottom on the left and right hand side.


This is a pretty straight forward swap out. Remove the small hose on the front of the valve. You need to squeeze the clamp on each hose and slide it back. Using a pick or screwdriver to wedge between the hose and the valve makes the hose removal easier. Remove the valve and spring clamps. The Valves come with worm clamps to replace with spring clamps, I recommend using these for 2 reasons. 1 you are never supposed to reuse a spring clamp and 2 it is much easier to install using the worm clamps. Choose which spring you want, I went with yellow, and unscrew the top of the valve and replace spring. The valve unscrews from multiple points so make sure everything is screwed on tight even the nipples on the sides. Install the valves the same way you removed them.



Now just reverse the process of removing to bumper.


I noticed a little but of sound difference and also seems to hold boost a bit better when shifting.


Enjoy!
 

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It looks like it's a Bosch 25mm diverter valve. Used in almost every VW/Audi turbocharged engine since forever. Maybe OP can clarify.
 

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I assume the flat 6 one's are some China made stuff? If we know the size we can get a quality unit. Forge etc...
 

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Looks like you can access those valves by just removing the under tray, no? It is cramped for sure but I don't think you absolutely have to take the bumper off.
 

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Discussion Starter #12
Looks like you can access those valves by just removing the under tray, no? It is cramped for sure but I don't think you absolutely have to take the bumper off.

It would be extremely difficult if not impossible. The bumper is easy to remove so that is the route i would take.
 

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Quick plug for Flat6.....I asked John a couple months back about the "coming" of the diverter valves for this car, and he went wayyy out of his way to write upa response to a couple of my questions.

If you guys have direct questions on why this unit was supplied, call/email John. He will give you the exact reason why. The guy is top notch on customer service.

That said, the factory diverters are junk. I have had multiple turbo BMWs and those diverter valves were always troublesome. (Hence the username haha) but changing out the valve to a much more reliable option is cheap insurance. To note, for anyone that doesn't know a diverter valve is a Blow off valve. The only reason why a diverter is called a diverter and not a BOV is because the diverter recycles back to the intake, not to atmosphere.

Remember soccer moms mostly buy these cars and soccer moms don't want to hear woosh woosh when the car is driving to the local mall.
 

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If this BOV doesn't increase the Whoosh sound why isn't the dump into the environment made for the macan's? just curious, I love that Whoosh sound and I think it would go great with the "sleeper" look of the Macan.




Quick plug for Flat6.....I asked John a couple months back about the "coming" of the diverter valves for this car, and he went wayyy out of his way to write upa response to a couple of my questions.

If you guys have direct questions on why this unit was supplied, call/email John. He will give you the exact reason why. The guy is top notch on customer service.

That said, the factory diverters are junk. I have had multiple turbo BMWs and those diverter valves were always troublesome. (Hence the username haha) but changing out the valve to a much more reliable option is cheap insurance. To note, for anyone that doesn't know a diverter valve is a Blow off valve. The only reason why a diverter is called a diverter and not a BOV is because the diverter recycles back to the intake, not to atmosphere.

Remember soccer moms mostly buy these cars and soccer moms don't want to hear woosh woosh when the car is driving to the local mall.
 

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The reason you cannot dump to the environment is that the ECU accounts for the diverted air into the MAS. Some older ECUs dont do this (for example the N54 engine BMWs) however the N55 engine ECU did not allow atmospheric dumps. Remember that the diverted air is air that has had work applied to it by mechanical components of the engine. That amount of air would be considered a loss of efficiency.

Obviously John should chime in on the research that he has done, but from what I understand about the upgrade, the Diverter is significantly more reliable and more consistent. Remember this diverter valve protects the charge side (discharge side) of not only the intake but the turbo. It may seem insurmountable, buy when the turbo shaft is spinning at 50k RPM do you really want to shock it momentarily with an overboost spike? No thank you.
 

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The reason you cannot dump to the environment is that the ECU accounts for the diverted air into the MAS. Some older ECUs dont do this (for example the N54 engine BMWs) however the N55 engine ECU did not allow atmospheric dumps. Remember that the diverted air is air that has had work applied to it by mechanical components of the engine. That amount of air would be considered a loss of efficiency.

Obviously John should chime in on the research that he has done, but from what I understand about the upgrade, the Diverter is significantly more reliable and more consistent. Remember this diverter valve protects the charge side (discharge side) of not only the intake but the turbo. It may seem insurmountable, buy when the turbo shaft is spinning at 50k RPM do you really want to shock it momentarily with an overboost spike? No thank you.


That loss of metered air would only cause the mixture to go rich for a quick sec, that’s not really a big deal.
 

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Thanks for the install guide!

Just a note on the diverter valve kit. I spoke about this some time back, we ended up sourcing from a company who already makes diverter valves for other clients. They had something almost off the shelf that just needed a tweak to work on the Macan. We have tested for about a year now and have 5 independent beta testers who have had them installed for 6+ months.

Personally, I would have liked to done a bottoms up development on these but the expense was too great and there wasn't a chance we could offer competitive pricing if we went that route (estimates were going to price them in the $570-600 range). Admittedly, something like Forge is going to be a nicer unit but we haven't had any issues and we have a validated solution.
 

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Just wanted to bump this thread to give OP and [email protected] some feedback and support.

I already had the following two installed for about 6k miles:
Flat 6 High Flow Intake System
Flat 6 Stage 1+ Cobb Tune


Diverter Valves Installation Notes:
- The pictures and instructions from OP were spot on for all the necessary steps. It took me 2.5 hours to complete by myself. That included time setting up my QuickJacks and putting everything away.
- One part that OP kind of skimmed over, was actually the most difficult part for me -- disconnecting the two wire harnesses in the passenger side wheel well. My efforts were futile and frustrating trying to disconnect it from the back side. What I eventually did was safely slide out the front bumper just couple of inches. Once I did that, there was significantly more working room to reach the two harnesses from the FRONT, through the bumper's intercooler ducts.
- Another area of difficulty was trying to get the OEM hose clamps off with pliers. The OEM ears on both of mine were facing into the engine bay. Nearly impossible to grab with pliers. I thankfully already had a set of Flexible Hose Clamp Pliers (the kind on a cable), and it is an absolute must for this install IMO.
- I agree with OP that trying to do this without removing the bumper would be near impossible. That stuff is on tight and in very closed quarters.

Post Diverter Valves Upgrade Experience:
- I kept the pre-installed silver springs in the unit, did not swap to yellow like OP.
- The boost hold is SIGNIFICANTLY more stable. With the Stage 1+ tune and OEM valves, the turbo pressure would frequently "flutter" on anything >7PSI. With the Flat6 valves, I can now hold up to 12PSI all day long.
- Pressure of >12PSI has risk of the flutter, but much less frequent still.
- The "upshift bang" from the exhaust is always there now. I used to only get it when the OEM valves were able to hold without fluttering and I hit a high RPM upshift.

All in all, I absolutely love the upgrade and would recommend anyone with a Cobb Tune to definitely order and install a set. The feel and sounds after the upgrade make the car even more fun to drive.
 

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- I kept the pre-installed silver springs in the unit, did not swap to yellow like OP.
I can now hold up to 12PSI all day long.

- Pressure of >12PSI has risk of the flutter, but much less frequent still.
Great feedback. Do you wish you would have changed out to the Yellow springs?
 
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