There is no file size limitation for IR data. The data is converted to a proprietary format optimized for the speaker simulator.
Note: The IR Loader is included in BOSS TONE STUDIO version 4.1.0 or later. GT-1000 system program version 4.00 or later is required. For GT-1000CORE, system program version 2.00 or later is required.
For more details on loading IR data, refer to the GT-1000 Ultimate Guide Video Series: