The iH8Sn0w developers team has released Sn0wbreeze v2.9.14 that includes support for a tethered jailbreak of iOS 6.1.3 over A4 iDevices. According to iH8Sn0w tweet the latest Sn0wbreeze also includes APTicket validation.
Download Sn0wbreeze v2.9.14 for Windows