[wwc310]

I know there are tons of threads out here already regarding the golf tee mod and the effects it has on performance. I don't want to start an opinionated debate here. Rather, I was wondering if anyone has dyno results of the same vehicle with as well as without the mod.

In many of the threads I have seen, people claim that they have seen dyno results or have done them themselves. Some people believe that this reduction of back pressure reduces torque and I wanted to see actual results to back this up. However, others have said that this has no effect on torque and the flap is only used to reduce exhaust noise.

Can someone chime in with their results?

Thanks

[Kolyan2k]

Originally Posted by wchilds310

I know there are tons of threads out here already regarding the golf tee mod and the effects it has on performance. I don't want to start an opinionated debate here. Rather, I was wondering if anyone has dyno results of the same vehicle with as well as without the mod.

In many of the threads I have seen, people claim that they have seen dyno results or have done them themselves. Some people believe that this reduction of back pressure reduces torque and I wanted to see actual results to back this up. However, others have said that this has no effect on torque and the flap is only used to reduce exhaust noise.

Can someone chime in with their results?

Thanks

both people who told you it reduces torque and flap is to reduce noises are wrong

flap is there to warm up the cats and it has no effect on any performace so doing dynos is pointless.

[Meeni]

Could it damage the cat then ?

[Slow_335i]

Is this a serious thread? Wtf?

[Kolyan2k]

Originally Posted by Meeni

Could it damage the cat then ?

no, its environmental feature

[Slow_335i]

Originally Posted by Meeni

Could it damage the cat then ?

No it'll only provide a large surplus of power!!

Probably a good 70+hp

[wwc310]

Originally Posted by Kolyan2k

both people who told you it reduces torque and flap is to reduce noises are wrong

flap is there to warm up the cats and it has no effect on any performace so doing dynos is pointless.

That's what I figured. I pulled all this from the 1addicts forum. They had pretty heated debate going on over there.

Thanks

[idrift4wd]

You do know that the exhaust flaps open up eventually. lol

dyno isnt goin to show anything.

[username604]

[Meeni]

Originally Posted by Slow_335i

No it'll only provide a large surplus of power!!

Probably a good 70+hp

Don't be facetious. Failing the emission test and having to buy a new cat is quite expensive. Nothing to be amused when it happens.

If you tell me that the Tee mod prevents the cat from reaching operating temperature, that has the potential to clog it, and fail the emission test later down the road (or not, hence the question).

[Kernel Kurtz]

I have the BMW performance exhaust from the factory. No flap.

Does not make any difference to anything except noise levels.

[Slow_335i]

So I just removed my rear seats and was wondering if anyone has a before and after dyno sheet...

Also will this harm my cats?

[Kolyan2k]

Originally Posted by Meeni

Don't be facetious. Failing the emission test and having to buy a new cat is quite expensive. Nothing to be amused when it happens.

If you tell me that the Tee mod prevents the cat from reaching operating temperature, that has the potential to clog it, and fail the emission test later down the road (or not, hence the question).

cats dont work when cold at initial start up, flap keeps hot exhaust gases inside to warm them up quicker. most cars obviously dont have those flaps, but some (or many) modern cars do.

thats also one of the reasons all manuals will tell you NOT to warm up the car and instead just start driving. they dont want you siting in the parking lot polluting the air

[Meeni]

Alright, since it took me more time to respond to mockery than checking for myself, no, it cannot damage the Cat. Case closed

[rjrankin83]

So to add on to the noob questions. It's easy and I'm lazy, so is there any harm in just unplugging the plug in the driver side taillight? Or do I have to crawl under my car and shove a golf tee into the line?

[Kernel Kurtz]

Originally Posted by rjrankin83

So to add on to the noob questions. It's easy and I'm lazy, so is there any harm in just unplugging the plug in the driver side taillight? Or do I have to crawl under my car and shove a golf tee into the line?

I've heard that unplugging throws hidden codes but can't verify. Golf tees can become hard to remove over time, and you still need to put a cover over the solenoid connection to keep debris from entering.

Tubing clamps are a better solution.

http://www.grainger.com/Grainger/tub...071&sst=subset

[roadkillrob]

It has nothing at all to do with emissions or it could not be legally disabled - PE exhaust would need to say for off road use only if disabling the flap messed up emissions and a non functional flapper would need to set the check engine light if it was part of the emissions requirements.

It is purely to pass the noise tests at certain RPM's that sound levels are measured at, then can open to allow more flow and better sound at higher RPM's.

Torque - no difference, that is controller by how quick boost is built and how high boost pressure is, that is controlled by the wastegates.

[thecadman99]

Originally Posted by Kernel Kurtz

I've heard that unplugging throws hidden codes but can't verify. Golf tees can become hard to remove over time, and you still need to put a cover over the solenoid connection to keep debris from entering.

Tubing clamps are a better solution.

http://www.grainger.com/Grainger/tub...071&sst=subset

I unplugged mine for a few days, and bmwlogger software showed a code relating to the flap that torque did not. The car knows if you unplug it...ewwwww spooky.

[Kolyan2k]

Originally Posted by roadkillrob

It has nothing at all to do with emissions or it could not be legally disabled - PE exhaust would need to say for off road use only if disabling the flap messed up emissions and a non functional flapper would need to set the check engine light if it was part of the emissions requirements.

It is purely to pass the noise tests at certain RPM's that sound levels are measured at, then can open to allow more flow and better sound at higher RPM's.

Torque - no difference, that is controller by how quick boost is built and how high boost pressure is, that is controlled by the wastegates.

PE exhaust is after market. All car manufacture tests are done on stock. Better emmisions is good for BMW, no body cares what you install after that.

PS. BMW tech told me its to heat up cats. Everyone who done gold tee mod done it for abit more noise that's why everyone is saying its to reduce noise.

I know some cars use butterflies to control noise, others to regulate back pressure, it just might not be the case with 335i

[roadkillrob]

Thank you for your email to BMW Customer Information.

We can advise that the exhaust flaps adjust at differing engine speeds in order to make the most effective use of the exhaust silencer. When the vehicle is running at idle or at low RPM, the flap ensures that the exhaust gases use as much of the silencer's volume as possible, keeping exhaust noise down, e.g. when you're in slow traffic or driving in high gear.

Whereas when the vehicle is running at high RPM, the exhaust flow characteristics are adjusted by the flap to give the exhaust gases a more direct route through the silencer, thus using less of its volume. This also has the effect of allowing the engine to rev more freely as there is less restriction on the exhaust flow.

The primary reason for the flap is to make the most effective use of the exhaust silencer volume at differing engine speeds.

We trust this information is of some assistance to you but if we can help you further at any time, please do contact a member of the BMW Customer Information Team.

Yours sincerely

BMW Group

[Kernel Kurtz]

Originally Posted by Kolyan2k

PE exhaust is after market. All car manufacture tests are done on stock.

No. My car, with both PE and PPK2, passes all emissions tests or they would not be allowed to sell it through the dealerships.

Not saying it couldn't have more emissions than without a flap, but it is legal and fully warranted and if I cared I'd own a Prius anyway.

[Kolyan2k]

Why wouldn't it pass emission... its just a flap, even if you remove cat completely it will still pass. It has nothing to do with passing state inspections. Every car manufacture is trying to make their cars greener