Hi Salvatore....welcome to the Club
Here is a link to a Tyre Pressure guide http://bit.ly/tyrepressures
If in doubt I would probably work on the principle that it is slightly better to have a little more than less but I would probably take it to 1 or 2 psi around the 33psi (e.g. 34 - 35 psi) and see how the handling is affected while checking the wear pattern on the tread.
Bear in mind also, the tyre temperature when checking pressures, as that alters considerably when the air temperature inside the tyre is increased (which can rise quite a few psi when the tyre is hot)....also bear in mind the accuracy of the pressure gauge you are using....the ones on the pumps at the petrol station are usually way out of calibration so you are better off having a pocket type gauge (either manual or electronic type).
Cheers, Trevor