We just covered iH8Sn0w has updated iReb to r5 version. The key feature of r5 is to help bypass iTunes errors such as 1600, 1601, 1602, 1603, 1604. Now here is the how-to.
Step 1: After the download process open iReb and select your device.
Step 2: Make sure that you have turned off your device, then press the Power button and the Home button in the same time for 10 seconds.
Step 3: Release the Power button, but keep holding the Home button for 30 seconds.
Step 4: Wait for a moments and when iReb r5 finished, start iTunes and restore.
And just keep that in mind, iReb r5 is only for Windows system.