heh, you'd need both unless you got V44. Gt1, afte V44 is only diagnostic, while if you wish to update, authorize or activate modules you need SSS, which is the orange OPS head. GT1 is the yellow head, V44 and before V44 will allow you to do both with this tool, but as it V44 is a bit old (Around 4 years now) what it can do will be limited compared to what a newer Gt1 DIS system can do, and a SSS system. If you're interested, I'm selling a Gt1 complete system for 1900$.