Depends on if it is a Ju188E with the stopgap engines or a Ju188A with the engines it was intended to have. The airframe was ready before the intended engines had been fully developed. Consequently the Ju188E is notably slower than the Ju188A.
I missed this one, the 188E stopgap engines were BMW 801D2, a whooping 75PS weaker than the Jumo 213 of the 188A, good for a 20kph difference between the variants (Nowarra).
WOuld love a Ju-388, but if the He-177 is controversial imagine the Stortebecker!