As Chris says, check your suspension settings against those in the handbook. Check your tyre pressures too and tyre sizes/aspect ratios as all these things can have a big effect on handling.
I'm still running Pirelli Diablo Rosso 2s and have always found the handling to be pretty sharp, certainly more so than the classic Monster like my old S2R. I've certainly never had any problems with understeer.
One thing you could check easily is whether the forks are correctly positioned in the yokes. They should be as per this diagram...
and I've seen at least one example where the forks were too far through the yokes, which would slow down the steering.
Although I've now got an Öhlins shock and K-tech forks, that's more for ride quality as I've never had an issue with the actual handling, even on standard suspension.