But to answer your question - no, the brake booster doesn't need to come off. All access is from the cowl, but you do have to pull off the plastic bits under the wiper all the way down to the cabin air filter (while you're in there, you may as well replace them as well).

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Robert Fini

'12 ML350 BlueTec, 87k
'06 E320CDI, 270k
'05 T1N Sprinter 2500/Pleasure-Way Plateau TS, 69k
'97 C36AMG, 313k (son's)
'94 E320T, 249k
'93 190E Sportline LE, 168k (daughter's)
'84 190E-2.3/5spd (Stage Rally Racer)
'66 230 W110 Sedan (Barn Find, Vintage Racer build in progress)