I have the Fut S9550 servo in mine...it is great...provide plenty of room for your electronics. I've got the 3pk and HRS set-up as well.
Awesome combo. get the GT7 over the Q2. But if you have the extra cash...look into the HB Hara Twister Speedo...it's purple and looks great in the car. Made by KO..basically identical to the VFS-2000 esc.