I found removing the air restricting snorkel to the air cleaner added a nice boost to my 380SL. Just take the air cleaner off and drill a few aluminum rivets out. You can always reinstall the snorkel with small screws and nuts if dissatisfied. The 560 engine wisely uses 2 intake snorkels. I had read about this modification on this forum last year. You can only process as much air as the smallest opening in your intake system will allow in. MB probably used that snorkel for quietness but it almost seems like a design flaw to me. My mechanic liked the idea and felt it necessary to make the fuel mixture a little richer due to the increased air intake. I used a piece of door edge protector plastic chrome to dress the air cleaner opening with but that was not really necessary, just for looks.

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John
'02 Isuzu Axiom Canal Blue Mica "Wonder Car"
'02 Isuzu Axiom Garden Green Mica from Alaska "Sara"
'97 Ford Taurus Wagon 225,000 miles Intense Black "Batmobile"
'91 560 SEC Ice Blue Metallic "Big Benz"
'84 380 SL Astral Silver "Pretty Girl"
MBCA member
Chance favors the prepared mind.