Turkish Airlines will upgrade the evening TK1491/1492 from the B737-700/800 to the B737-900/A321 over the winter.
Also, this flight goes from 4 weekly over winter to 5 weekly, making MAN-IST 19 weekly in winter.
The A330 is also making frequent visits on the TK1993/1994 over winter too.
Turkish seem to be holding their own against the might of the MEB3 at MAN!