Well even though this thread is old, reading it tonight motivated me to perform my very first mod. I had some black zip ties lying around, and VERY EASILY located and kinked the vacuum line. Anybody reading this wondering if you can do this, stop reading and go look under your car left of your muffler... I'll wait..... Now wasent that easy?
My impressions are as follows: I allowed the car to warm up before judging. For the record my un-modded car's exhaust valve is open while off, and at idle. Same with the golftee mod. Revving at stoplights I can hear a difference, it sounds more airflow is moving, and at low rpm speeds (10mph in 2nd gear) the exhaust hum is more noticeable, by a very small amount. Probably my most observed change is throttle response. The rev's (sitting still) seem to rise/fall a little quicker.
IMO a mod worthy of keeping for a little while, not to mention its free... and takes less time to do than to reach this portion of my review. Super freaking easy, if you can tie your shoe or breathe air you can perform this mod. Just try it, it was fun actually just working on my bimmer, even though it was for only like 8 seconds.
Thanks for this thread!