Easiest Sport exhaust mod ever!!

[mixterk]

On 330's the stock exhuast system has a vacum operated valve which closes a gate on the inside pipe, this has the effect of a baffle which keeps the noise levels down at lower revs. This unit is situated under the rear bumber on top and to the right of the rear siliencer box, easy to get to.
If you disconnect the vacume pipe from the exhaust vacum control valve which operates the gate, it stays open at all times, just remember to plug the pipe with a golf tee or something. The result is the sound of a sports exhuast but with the money still in ya pocket. It sounds great, best freeby around..... :P

[david]

can you post a pic or pics of how to do it?

[RR330i]

David, this was discussed a while back.
Then I did the mod. Its very easy to do and the exhaust note is
a little throatier, especially in the 1000-3000rpm.
fcotanis did this, but thought it was a bit too loud.?.?.? :screwy:
Here is the link to the previous post... hope it helps.

By the way, aren't you moving to the big city & selling your car?
exhuast mod link (http://www.my330i.com/forums/viewtopic.php?t=1181&postdays=0&postorder=asc&start=0)

[david]

yes, but until i sell, if it's REALLY easy, i might enjoy the throatier sound :lol:

[morcheeba]

I was digging around the trunk (and I mean digging... as in behind the liner), and I found what appears to be the solenoid that connects to this vaccum tube. It's controlled by the computer, and there's an error code that gets stored if the solenoid is disconnected. I haven't tried messing with this yet...

I've got an idea, though: I'm thinking of building a relay that's controlled by an unused button on the steering wheel, so I can turn it on and off easily. Sound interesting?

[david]

heh heh heh....a deep exhaust on command? cool shit!!!!

[mixterk]

The pipework stays connected except at the vacum diaphram ontop of the silencer box. With the pipe plugged (golf tee) the computer doesnt know any different. It has zero effect on performance it just sound great. Enjoy!!! :twisted:

[RR330i]

This took me all of 5 minutes, and I was elaborate in my ways.
Used correct size screw to plug up hose, then duct tape seal.
Used a wire tie to attach under bumper.
Also duct tape up on top of muffler.

I don't hear that much of a difference from inside the car, but it sounds so hot when I hear it drive away! :wink:

[marlonn]

:? Guys, I have been following the discussions on this exhaust flap modification and decided to check it out. I have a 2003 330i Individual and when I went to check, to my surprise this thind was already disconnected and fitted neatly into the individual bumper.
My car is brand new so it had to come from the factory like this. Oh and by the way the end of the hose is not plugged, which confirms that this gadget is for sound purposes only. I am going to findout from BMW SA wether all 330's in SA are like this or just the individuals.
As for the exhaust note, it does have a much deeper sound at low revs compared to non 330's.

[david]

marlonn, thanks for that interesting info! keep us posted!!!!

[yrp888]

After months of thinking about this, I finally did it a few weeks back, and I am mainly impressed.

First - the procedure. In Australia buyers have a morbid fear of anything that deviates a BMW or Porsche from "stock". Don't ask why, just stupidity if you ask me. So I was interested in a mod that would be really hard to pick, even for a dealer.

I had a spare roller bearing cage and I ground off the outer race to reveal a bunch of perfectly nice 1/4" ball bearings. Taking one ball bearing I inserted it into the end of the vacuum hose using a bit of silicone grease to ease it in, then using a 5mm cap screw wound it in until the ball bearing disappeared into the hose about 10mm. I put a small black cable tie behind the bulge as insurance in case the vacuum managed to suck the ball bearing further down, unlikely but I'm the son of an insurance agent, what can I say?

Then I replaced the hose back onto the vacuum diaphragm. Unless you look really closely it would be extremely hard to pick, it looks as though the hose is correctly attached, and doesn't involve screws, duct tape, loose hoses etc. Very neat.

Pro's - increased fuel consumption, better low end responsiveness, lugs in taller gears much easier. I was quite astounded at the improvement in fuel economy. I normally average 9.5 l/100km (29.6 mpg) city, but this minor mod improved it to 8.9 l/100km (31.7 mpg). Doesn't sound like a lot but useful in Australia where we pay 3-times what you pay for fuel in the US, but yields a significant extra 40-ish km for a tank (I know should be about 100, but I fill up early). I doubt if the highway consumption will improve by the same amount ... yet to test this.

Con's - The cabin is very boomy in the 1500-1800rpm range when driving within the pitiful Sydney speed limits. But I can live with that minor inconvenience by turning up the radio to compensate.

Summary - an excellent modification and well with the effort which was nil!

[Gomer]

Does it sound like this?

http://www.theguitar.net/bmw/ruby1.mp3

[skeedameat]

I was fascinated by this easy little modification, so I did it this morning. I have a hard time noticing any difference, if any at all. I'm wondering if I did it correctly. I took the vacuum hose off and put a golf tee in the end of the hose and tucked it under the bumper. I'm assuming that was all I needed to do, but if there were any steps that I omitted could someone let me know.

Thanks

[NOVAbimmer]

yeah, I just did it...didn't really notice a difference. It's a tiny bit throatier between about 1k and 1500 rpms...but other than that....eh