Bought the GT3 with the Michelin Pilot Sport Cup fitted from factory but would be driving this car as a daily driver. Can I substitute it with the standard PS2 tires with no side effects in terms of handling (both dry & wet) and straight line performance?

 

yes you can sub the ps2

 

PS2's are good in the wet, MPSC are not IMO.

 

Ok. But is it a common practice to replace it with a regular street tire on this car, or MPSC has been specifically engineered for this car in that there would be unfavourable handling characteristics upon doing so?

 

For street use the PS2 is a better alternative. Some tests have been done that the PS2 is not that far off in times on the track. To answer your question, you will not harm the handling of the car (for street purposes) by going to this tire. Assuming you are not driving 10/10ths on the street.