downhill shouldn't matter should it?...it's the actual speed...not the engine's capability that causes the speed governor to hit...now thas diff from the rev limiter which is stopped b/c the engine aint gonna go anymore...anyway...EX ecu should get rid of it...but if ur still pulling, even very slowly, u haven't hit it...cuz i pull pretty good till 112/113, which is where i think mine is...my car's older gen btw...and when u hit it...it just like jerks/jumps and holds u back