I'm running an Executioner and will use it with 13.5 or 4300. I decided to mount my GTB on the right side of the chassis. I removed the cooling fan first. I ended up placing the speed controller on the right rear as close as I could to the t-plate without it interfering with pod movement and as far back without hitting the chassis brace. I positioned the speed control with the motor/battery wires facing to the left of the car and parallel to the t-plate. This mounting position also places the wiring harness side facing the right side of the chassis and the side with the indicator lights facing to the rear.
I routed the battery wires under the center shock. I used a small piece of heat shrink tubing on both the red/black wires where they went directly under the center shock to keep them from moving around excessively. I left them a bit long as I prefer to connect my batteries as far left as possible in case I need to solder them on with the body on the car.
I routed the motor wires over the pod to the motor. The advantage of where I located the speed control was that I could see the ABC label on both the speed controller and the motor from the left side of the car. Since this was the first time I've used a brushless motor, this was a bit of a bonus. Again, I used a bit of extra wire length with the motor wire to avoid any chance of the pod binding and to prevent any stress on the circuit board.
I routed the motor sensor wires in front of the motor underneath the cross brace. I'm not really happy with the way this looks, but I was in a rush to get the car on the track. Make sure you use the included sensor wire management that comes with the GTB to protect all the wires.
The wiring harness for the receiver was a bit ackward. Even though it was a long cable, it didn't reach neatly to the receiver. I have the receiver on the front of the battery tray. The receiver harness needed to go from the right rear to the left front, so there wasn't any great way to do this. I may go back and shoe-goo the harness wire to the chassis to give it a cleaner look.
I did not remove the GTB capacitor. I mounted it to the chassis just in front of the speed controller using servo tape. I didn't give the tape enough time to set and the capacitor popped of during racing. I may end up using shoo-goo to mount that more permanently to the chassis.
I'll try to dig up my digital camera and post a photo of my car and speed control. I won't say that it is the cleanest solution in the world, but it looks okay. I wouldn't say that having the speed control on the right side hurt me as I was turning good laps on my first time out.