Not meaning to make light of your situation, but i've only ever had great experiences from my Novak BL systems. That includes the ORIGINAL ss5800... it never thermalled on me and i was running quite a bit below recommended gearing.
My GTB with 5.5R HAS thermalled on me on very hot days, when the esc fan had turned off(jammed by track debris). With the debris cleared the only other reason for a thermal was from the motor. Again, running overgeared and on a 38degree day (Celcius..)
All other times, it has been great.
How is the system set up in your car? what kind of track are you on?
I run mine with a fan on both esc AND motor. It is afterall a reasonably low turn system. With the current draw and enthusiastic use that is typical of high speed rc, it's only reasonable to expect the motor AND the esc to heat up in use...
Have you talked to Charlie from Novak CS?.. they are exceptionally helpful.