Yeah I think times in the 1.52's are possible. My best was a 1.53.973.
I posted it here before but it is not here anymore as well as some other posts of other people. I rode it on the 7 stars Honda though and it was not a perfect run.
But yeah if u practice a lot, times in the 1.52's should be no problem.
I did not play the game in a while now cause I am addicted to MotoGP4's online mode
But TT is so much better when it comes to graphics and physics and the overall bike feeling and handling.