If you say no to 6.4GB one-off.
You don’t have to wait the best part of an hour for Gran Turismo 5 to install – you can opt for the game to unpack chunks as you play, Sony explained this afternoon.
“GT5 gives users the option of an install,” Sony pointed out. “This makes loading times throughout much faster but is not a requirement when first playing.
“If users choose not to install the data straight away it will do it in stages as news areas, tracks, etc. are accessed during normal gameplay.”