n54 = more power
n55 = more reliable power
I say this with the notion that both do not have upgraded turbos, oil coolers or radiators.
The n54s biggest downfall is cooling and wastegates. The above three items will fix those issues.
I enjoyed my n54 335s and n55 135, but the 135 never had any issues whereas my 335s did.
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2017 MB C63 S Coupe - DINAN | MODAL WORKS
retired: GranTurismo MC, Giulia Quadrifoglio, B8.5 RS5, Q60 RedSport, e82 135, F80, e92 M3, e90 M3, (2) e92 335, B8 S4, C209 CLK55 AMG, e46 330
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