I used it on my s320 gas.The tape is leak prooft,and sticks like super glue,I'm talking about the tape that is alminum.Not aluminum colored.Besides less air(leak thru boot should lean her).Less air over maf sensor.It can't dump more fuel with no air.
To pass emissions here a old trick,add 4 oz. acetone to each 10 gals. gas or diesel.
This raises combustion by 10 to 20%.Better mileage,power,and pass emissions.
Also the first oxy sensor controls rich or lean.I have cleaned them with carb. cleaner,and blow dry them.The'll last another 100,000.I did mine.

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1999 w140, quit voting to old, and to old to fight, a god damned veteran, deutschland deutschland uber alles uber alles in der welt