Thanks Bill, my overall weight is 76-77kg (myself and the bike) which is about 2kg less than before with the new bike, never felt such an issue with my old bike which has Conti Ultra Race tyres though these tyres don’t have too much good reviews for wet condition. Don’t know if the grip-loss is related to the 2kg loss or the new tyres. Had a look on Grand Prix 4000S spec it seems to be a super gripy tyre with 330 threads per inch, the Michelin under question has only 127 thread counts, maybe that’s where the problem lies.
Cheers, Nirvan