csdspeed - The first Brushless System I got was Novak's 5800 Super Sport around 3 years ago and I installed it on my XXX-4. It had no problems fitting but I quickly learned that I had to cut strategically placed holes or vents on the body to allow for better air-flow and ventilation. Furthermore, I even bought a small Reedy fan to help keep the ESC's temperature down to avoid thermal shutdowns. Other than those minor adaptations the Super Sport worked great on my XXX-4 (now a G+) as well as on my other 4WD kits in general. The GTB should fit but you might just have to move it's fan to the side rather than keep it directly over the ESC in order to fit the body perfectly. Hope that helps!
Yes, the Sphere with it's heatsink should fit without any problems. Just know that LRP recommends that Sphere owners buy their
Cooling Set from them separately (Fan, Capacitor, etc.). You only learn about this after purchasing the Sphere and reading it on their User Guide manual.
