So, for just $15 you can get 30PSI?


Ready to race!
Niles, MI
2006 GTI MkV, Red
the diverter valve by forge is also for the 2.0 t

You are incorrect, sir. The diverter valve used in the 1.8T (which these springs are made for) is completely different than the one in our 2.0T engines. They ARE NOT interchangable in any way. Also, looking at Forge's web site, all I can find are blow off valves for the 2.0T - who would want their car to sound like a reject from "The Fast & the Furious"?


Rally Car Champion
Selden, New York
Actually this device is for the 2.0t. And it sounds just like a bov. there is no difference in devices and those springs work for either. here is the desc. from forge. and a link to the part's page.
Yet another first for the Volkswagen and Audi Tuning Market from Forge ! With the introduction of the VAG 2.0 litre FSi Turbo Engine, and the procurement of our own development/project car, we have developed a Patented Atmospheric Blow-Off Valve adapter specifically designed to fit this application. Simple in execution, yet offering the desirable atmospheric blow-off valve sound, this product has been designed to be fully compatible with the Bosch ME9 engine management systems employed on the following vehicles: Audi A3 2.0T FSI Audi B7 A4 2.0T FSI Volkswagen MK5 Golf GTI/Jetta GLI 2.0T FSI.


Touring Car Champion
I've always thought diverter valves and blow off valves were the same thing with people thinking that they are called different things because most people associate blow off valves with those which vent air externally as opposed to recirculating it back into the intake. Also see: The fact is whether they recirculate or vent the air externally, both still use a spring.

In fact I used to have a hybrid type blow off valve on my Nissan 200sx/Silvia which vents both externally and also recirculates air which is adjustable via spring tension so that the harder you set it, the more air it will recirculate back into the intake and vice versa. So would you call that a diverter valve or a blow off valve?


Drag Racing Champion
Knoxville, TN
Just to clarify. The way a diverter valve (or a blowoff valve for the first part) works is this: When you are on throttle the throttle body is open and the diverter valve is closed because there is no vacuum to open the valve. When you close the throttle there is vacuum behind the throttle body which opens the diverter valve to allow the turbo to spin down, releasing pressure. How this works is this. The valve is screwed in between the turbo and the throttle body. There is a hose going from the diverter valve to behind the throttle body. There is also a hose going from the diverter valve to the airbox(not on a blowoff valve, which is why a blowoff valve is often called an atmospheric blowoff valve).

Changing the springs in a blowoff or diverter valve only changes how much pressure it will withstand before allowing excess turbo boost to force it open, allowing of couse for the valve body not blowing apart.

I am not a writer, and having just had surgery, am not thinking perfectly clearly, but there is a better explanation here:

Hope this helps.


Rally Car Newbie
sublyme said:
I don't see how these would increase boost pressure, it would increase the resistance before the diverter valve releases the pressure
that is exactly right. the diverter valve acts like a blow off valve which prevents pressure from going back to the turbo and causing the turbo to backspin. you'll hear it clearly when the turbo has backspin. those springs are to set the pressure you want this valve to release boost after you shift gear or just let off on the gas


Drag Racing Champion
Knoxville, TN
blackmkv said:
those springs are to set the pressure you want this valve to release boost after you shift gear or just let off on the gas

That is not exactly right. The valve will release to a certain point (15psi for example) even when you are on throttle unless you upgrade the springs to for a higher boost.

I dont mean to be disagreeing with your entire post but just wanted to clarify on that one point.



Autocross Champion
Stamford, CT
Okay 2.0T engines use a SPACER.
These springs are for diverter VALVES such as the 007 ones for 1.8T or 2.7T engines.
I have an extra set of these for my B5 S4 somewhere.
Call Forge and see.
The BOV in the 2.0T is electronic.
Did anyone even bother to read the stickied pdf on the top of this forum.
Just read page 17


Touring Car Newbie
haha not only that the turbo on our cars are so small they would not be able to boost that high, if you look at a dyno chart we start to actually loose power at the thigher rpms on a chipped car anyways, and as to the fact that we are runn a 10:3 compression ratio, on the fsi motor doesnt matter as much notice i said as much the car uses a direct injection so instead of injecting the fuel before the cylinder head, this one actually injects right int he cylinder head thats why when u start your car it sounds like a diesel, by this being injected in the cylinder head and not before alow the gas to sprayed in a much more controled way and at a much finer rate alowing us to run higher boost, but 30psi would not go over good ive heard of that on race cars but for daily driveablilty you would have zero

Not only that but at running at higher boost you need to add just as much more fuel to the engine so you dont run to lean correct me if im wrong, and no if your thinking just add bigger injectors and that gives it more fuel, ya sure it will but it will also give u a rough idle and your economy will be zero, and add to that there are no injectors that i know of that are bigger

please im only an 18 yr old mechanic if ive got any of this wrong please correct me


Go Kart Newbie
The diverter valve does not controll boost. The wastegate controlls boost.
the 2.0t is a MAS air motor. Meaning it has a MAF sensor that measures the actual airflow into the engine so the ecc can calculate the proper injector pulswhith to reach the desired AFR. In a MAS system you need a diverter valve and not a blowoff valve. a diverter valve diverts the blowoff air and presure back into the intake AFTER the maf because its allready been metered. a Non MAS car such as a speed density system that uses a throttle position sensor allong with a BAP sensor does not measure actual airflow. it calculates it. those systems can dump the vented air back to atmosphere.
its all about the emisions and economy. if you dump metered air back to atmosphere then the mixture will be overly rich because the ecc is adding fuel in proportion to the metered air you just let escape from the system through the blowoff.


FIA GT Champion
Correct Fastlane. That is why it is really just a noise maker.