In an attempt to improve the boost response between shifts, I fitted a small plastic fuel filter (w123 plastic pre-filter) inline on the vacuum feed line going to the solenoid that controls vacuum feed to the wastegate actuator. I put it as close to the solenoid as possible. The idea is that the small filter acts like a vacuum reservoir so that when the solenoid opens up there is abundant vacuum standing by to close the wastegate quickly. Without the reservoir, the volume of vacuum needed to close the wastegate is limited by the small and long white plastic vacuum feed line coming from the brake booster. It “feels” more responsive, but I need to do more test taking it off and on, driving around, to see if it’s just my imagination. I’ve only driven it a mile to starbucks and back at this point. If anyone out there has a boost gauge installed maybe they can try it to see if the gauge provides more useful data. The feed line is the small white plastic line going to the top of the solenoid located under the MAF sensor, by the air filter box.

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1999 E300 DT