I have a enlarged displacement M103 modified by RENNTech. The cost of their labor, expertise, and parts was shy of $14k and that was 15+ years ago. If you have the time and money, you may be able to R&D or reverse engineer what they or AMG did but most will not or do not relative to the car's current value and the cost of a 500E. If you modify one thing, you need to modify all the matching components i.e. enlarging the intake won't help without enlarging the valves or head flow, and exhaust, and...

I thought of polishing the intake but then it's buried under the air cleaner and parts so that you wouldn't see it.

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'88 300TE, 175k, black RENNTech 3.6L Recaro C's AMG 1 SOLD
'92 500E, 110k, Spruce green, stock SOLD
'94 E320 Cabriolet, 130k, E500 wheels, Emerald green SOLD
'94 E320 Cabriolet, 110k, black, stock, SOLD
'88 300TE, 229k, dark grey, SOLD
'90 300CE, 212k, white, new paint, SOLD
'91 300E, 209k, white, rebuilt head SOLD
'74 914-6, grey, 2.7L 325hp twin turbo Audi conversion