Rockstar Games’ official Twitter customer support account is advising Xbox 360 users who are getting Grand Theft Auto 5 not to install both discs for optimum performance.
@TurianKnight We do not recommend that.
— Rockstar Support (@RockstarSupport) September 15, 2013
When pressed for further comment, they elaborated that the one install disc needed to run the game requires an 8 GB install. This install can be done on either the HDD or on a flash drive. However, they do not recommend installing the play disc. Rockstar did not provide any specific reason, but they promised to provide explanation when the game launches on their official support site.
On another end, Rockstar also confirmed that Grand Theft Auto 5 is a 38 GB install for PSN. This version will also require an 8 GB install. However, this reply implies even if you only have 39 GB available you will be able to get the game.
@vavaenzo Yes, 38 GB is required for the install but that is cutting it pretty close.
— Rockstar Support (@RockstarSupport) September 16, 2013
Rockstar provided more details about Xbox 360 installation in an earlier Q&A post on their site. If you are using a USB flash drive, it will need to be a 16 GB drive, with at least 8 GB available space and formatted to use on the Xbox 360. The main thing, however, is that Rockstar claims this game makes use of every bit of processing power on both consoles, being their most ambitious undertaking ever.
Of course, Xbox 360 owners usually install both discs for their games so that they can get the best performance out of it. Rockstar seems to imply there is an undesirable payoff for trying to do the same to their game. Could this be related to the new Grand Theft Auto Online mode? It doesn't sound gamebreaking since they did not make a bigger deal out of this. We won’t have long to wait for this one, as many fans are likely to try this come launch.
You can read other replies below.
@justinkeppler @Insanely_Bored @EliDrinksZona An 8GB install is required. For optimal performance, we recommend not installing the play disc
— Rockstar Support (@RockstarSupport) September 16, 2013
@justinkeppler @Insanely_Bored @EliDrinksZona There is a specific install disc with the 8 GB to install on the HDD or flash drive.
— Rockstar Support (@RockstarSupport) September 16, 2013
@mfw For optimal performance, we recommend not installing that disc. We will have more info on our Support Site at launch.
— Rockstar Support (@RockstarSupport) September 16, 2013