As long as you keep the overall diameter within specs you should be fine. WHenever you go up in size of a wheel say from 14 to 15 you go down in aspect sidewall height of the tire.
So 185/65x14" would be a 195/55x15", 16s would be 205/45x16"
You will get worse mpg if you go to a heavier rim, but the GSR and Si rims are lighter than I think than the steel wheels like 14s.
__________________
Sponsored by: KAM Racing Sports, Falken Tires, Progress Technology, Brady's High Performance, Taggart Performance Engineering, Rotora Brakes
Autocross is: 90% driver, 5% car, & 5%
CRAZY MOJO!
Autocross Help Page