If you need the suspension to perform as well or better than it currently does(given poor roads in your area?) definately do not cut the springs down.
I would suggest that it should never be done anyway, but that was a long and pointless discussion in another thread with owners of another Toyota model.....
Don't just modify your car for looks or because you think it looks ugly, plenty of people on this forum believe that the Celica looks just fine thank you.
I run 205/60/15's on my RA23 and they look fine, so 195/50/15's will be OK.
We almost always to a man, save the pennies and buy a set of heavy duty lowering (not super low) springs from someone like Lovells or Kings. They lower the car between 25 - 40mm, and improve the handling immensely.