ELEVENS

Too good to be true? Nope! We all love the Superman button (Sport mode) because it makes the car sound so much better, but I do NOT like the remapped throttle. It only makes it harder to shift. I own a BMW 330xi which also has a valved exhaust. A popular mod on that car is known as the "Golf Tee Mod". It works because the valve is "normally open", meaning that the butterfly valve is open without applying vacuum. So all we have to do is remove the vacuum and the valve will always be open! No longer will you have to press the Superman button every time you get into the car. Better yet, now you can hear your beast jump to life without those butterfly valves muffling that sweet music. Enjoy!

1st, you need one of these:
<img src="http://pictureposter.audiworld.com/109574/dsc_0028_small.jpg">

In this pic you can see the butterfly valve on the right side in the open position:
<img src="http://pictureposter.audiworld.com/109574/dsc_0024_small.jpg">

Here is the solenoid that controls it:
<img src="http://pictureposter.audiworld.com/109574/dsmall.jpg">

Use an end cutter to snip the clamp:
<img src="http://pictureposter.audiworld.com/109574/dSmal3.jpg">

Now plug the hose with a golf tee (shameless advertisement) and tuck it away. Repeat procedure on the other side and enjoy!
<img src="http://pictureposter.audiworld.com/109574/dsc_0010_small.jpg">

Parikh1234

how does this lead to better gas mileage and HP?

ELEVENS

99% hype. Usually though, free flowing exhaust will improve mileage and increase HP. YMMV.

gofastblue

If this really works, I'm going outside to do this mod right away!!!

West La

IMO. So my shifts are much smoother.

JDBlueAudiS4

gives me a chuckle. You do know that the only thing true in your statement is the better sound. Also if you don't have a clamp on there its only a matter of time before it falls out so make sure you put something on there to prevent it from falling out.

JDBlueAudiS4

all it does is make it sound better....

RI A6

If the exhaust valve is in the open position, there is better exhaust flow. Better exhaust flow will increase HP. The question is how much. We mere mortals without a dyno in our garage have no way of knowing. However, we do have the technology to monitor fuel consumption.

So on a long trip recently I monitored instantaneous fuel consumption with cruise control on a flat highway, while switching back and forth from non-S to S operation. My conclusion was that there is a 0.2 to 0.3 MPG decrease in fuel consumption (increase in mileage) while cruising at 70 MPH in S-mode.

ELEVENS

Sorry if I mislead anyone, the subject line of the thread was tongue-in-cheek right out of the playbook of aftermarket exhaust manufacturers. I guess some people take posts as matter-of-fact.

The fact is, no - I don't know that and neither do you. It's pure, unsubstantiated speculation. YMMV. If I gave a hoot about gas mileage I'd be driving a moped.

ELEVENS

The M5 guys know that they can't drive around all day with Sport off, then turn Sport on at a traffic light for a race and expect to launch smoothly and shift properly. Eveything changes when the throttle map is quickened, and it takes practice.